Thyristor Power Controllers

Thyristor Power Controllers Basic principles and tips for practitioners Manfred Schleicher Winfried Schneider Note This reference work has been crea...
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Thyristor Power Controllers Basic principles and tips for practitioners Manfred Schleicher Winfried Schneider

Note This reference work has been created to the best knowledge and belief. We assume no liability for possible errors. The definitive source of information is always the operating manual for the relevant device.

Preface In industry, power controllers are electronic devices that can be used to vary power, current, or voltage. These are typically thyristor power controllers. Typical applications are generally found wherever electrical power needs to be varied and is ultimately converted into thermal energy. Power controllers are therefore used in industrial furnace construction or plastics processing, for example. JUMO has been an expert partner for the industry for many years when it comes to thyristor power controllers. With the devices from the TYA 200 series, the company offers products for operating any electrical heating elements. The development concept focused on making startup and operation as simple as possible. Many standard applications with power controllers are relatively easy to use. However, in some cases, numerous points need to be taken into account for an effective configuration according to the power controller load. Considerations such as subordinate control loops, current limiting, limiting of the maximum heating element temperature, and reducing peak loads in the system play an important role here. This technical literature is therefore intended to serve as an effective and important guide in making the right decision for every application scenario. It provides important basic principles in general for thyristor power controllers and specific details for the TYA 200 series. It also offers useful assistance for practical use of the devices in terms of dimensioning, connection, and configuration. This new issue has been extensively revised and supplemented to provide a comprehensive insight into the entire subject. Fulda, Germany, January 2016 Dipl.-Ing. (FH) Manfred Schleicher

JUMO GmbH & Co. KG Moritz-Juchheim-Strasse 1 36039 Fulda, Germany Phone: +49 661 6003-396 Fax: +49 661 6003-500 Email: [email protected] Website: www.jumo.net

Reprinting is permitted if source is cited. Part no.: 00400481 Book number: FAS 620 Printing date: 2016-01-04 ISBN: 978-3-935742-05-4

Dipl.-Ing. (FH) Winfried Schneider

Contents 1

Thyristor power switches and controllers .............................................. 5

1.1 1.2

Thyristor power switches ................................................................................................... 5 Thyristor power controllers ................................................................................................ 6

2

Thyristor power controllers ..................................................................... 7

2.1 2.1.1 2.1.2 2.2 2.2.1 2.2.2 2.2.3

Operating modes .............................................................................................................. 9 Burst firing mode ............................................................................................................... 9 Phase control mode ........................................................................................................ 10 Combined use of burst firing mode and phase control mode .......................................... 12 Soft start .......................................................................................................................... 12 Switching to phase control mode via binary input ........................................................... 14 Burst firing mode with  start .......................................................................................... 15

3

Subordinate control loop ....................................................................... 17

3.1 3.2 3.3

U2 control ........................................................................................................................ 18 I2 control .......................................................................................................................... 19 P control .......................................................................................................................... 20

4

Dimensioning/operating mode/startup ................................................. 21

4.1 4.2 4.3 4.3.1

Dimensioning .................................................................................................................. Selecting the power controller properties for the heating element .................................. Connection in single-phase operation: phase/N and phase/phase ................................. Configuration ...................................................................................................................

5

Functions of the thyristor power controllers TYA 201/202/203 ........... 25

5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8

Manual mode .................................................................................................................. Load monitoring .............................................................................................................. Resistance limitation (r-control) ....................................................................................... Firing pulse inhibit ........................................................................................................... Dual energy management ............................................................................................... Monitoring of the mains voltage drop .............................................................................. Half-wave control for vibration drives .............................................................................. Connection via interfaces ................................................................................................

6

Thyristor power controllers in a three-phase system ......................... 33

6.1 6.2

JUMO TYA 202 – thyristor power controller for controlling ohmic-inductive loads in three-phase economy circuits .................................................. 34 JUMO TYA 203 – three-phase thyristor power controller ................................................ 36

7

Reference list ........................................................................................... 41

21 21 22 24

25 25 27 28 28 29 29 30

Thyristor Power Controllers

Contents

Thyristor Power Controllers

1 Thyristor power switches and controllers 1.1

Thyristor power switches

The thyristor power switch solution optimizes the purchasing costs for heating with electrical energy. The actuators are operated by direct voltage and switch the supply voltage to the heating system or block it:

Compact controller JUMO dTRON 304

SCR power switch

L1

N

DC 0/5 V

Heating element

Figure 1:

Thyristor power switch with controller and heating element

The compact controller works as a two-state controller in the case of thyristor power switch control.

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1 Thyristor power switches and controllers 1.2

Thyristor power controllers

Many applications require the use of thyristor power controllers. There are many reasons for this, such as greater control quality due to faster cycles and compensation for fluctuations in mains voltage. Current limiting and monitoring of the heating element temperature also mean that the heating elements operate safely. The energy management reduces the peak load in the system.

Figure 2:

Diagram of a thyristor power controller in a closed control loop

The thyristor power controller generally receives the output level yR (0 to 100 %) from a continuous controller as a 4 to 20 mA current signal and directs the electrical power (output level y) into the heating system in proportion to this signal. The thyristor power controller is supplied with alternating voltage.

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2 Thyristor power controllers Figure 3 shows the JUMO thyristor power controllers that are available for single-phase and threephase operation:

Figure 3:

Thyristor power controller TYA 201 (single-phase operation), TYA 202 (threephase operation in three-phase economy circuit), and TYA 203 (three-phase operation)

Thyristors are also used as switching elements in thyristor power controllers:

Figure 4:

Switching symbols for the thyristor with voltage UAC in switching direction

Once the gate has been controlled with a positive voltage towards the cathode (figure 4), the anodecathode path becomes low-resistance; this is referred to as firing the thyristor. It is not possible to use the gate for turning off. It will only return to the blocking state when the anode-cathode current falls below a minimum value, known as the holding current. In alternating current circuits, this occurs when the current passes through zero after every half-wave of the cycle. In the low-resistance state, there is a voltage drop between the anode and cathode – the on voltage – of 1 V to 1.2 V. The power loss produced by this is proportional to the current strength and heats the thyristor. In the blocked, high-resistance state, an off-state current still flows through the thyristor. This is 20 mA for a thyristor with a nominal current of 100 A, for example. As described in Chapter 1 "Thyristor power switches and controllers", page 5, the thyristor is used as a contactless switch in alternating current circuits. However, it only switches the current in the direction of the cathode. Therefore, to switch alternating currents two thyristors are needed in an antiparallel circuit (see also Figure 1).

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2 Thyristor power controllers Thyristor power controllers contain control electronics as well as thyristors (Figure 5):

L1 N/L2

L1

N/L2

Control electronics

Controller

SCR power controller Heating element

Figure 5:

Schematic of a thyristor power controller with control electronics and thyristors, controller, and heating element

The controller provides the controller output level (0 to 100 %) as a continuous signal (for example 4 to 20 mA). The power controller switches the voltage supply to the heating element for a percentage of the time accordingly. The power at the heating element is controlled as a percentage of the controller output level.

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2 Thyristor power controllers 2.1

Operating modes

The thyristor power controller operates in burst firing mode or phase control mode.

2.1.1

Burst firing mode

In burst firing mode, complete sine waves of the mains voltage are either switched through to the load or blocked.

U Load

t

Figure 6:

Burst firing mode

___ Load voltage ---- Mains voltage Figure 6 shows the sine waves of the mains voltage curve (usually 50 Hz). In the example the thyristor power controller requires power of 60 %: three mains voltage full waves are switched to the load while two full waves are blocked. The voltage supply is applied to the heating elements for 60 % of the time and the power produced is 60 % of the maximum value. Per default, the thyristors are switched on and off once in a defined time (typically 500 ms). This time is known as cycle time and can be varied. As a second option, the power controllers switch as frequently as possible. The thyristors are fired at zero crossover and only complete sine waves are switched through. This produces neither harmonics nor reactive power. Chapter 2.1.2 "Phase control mode", page 10 One disadvantage of this otherwise unproblematic operating mode is the voltage fluctuations that can occur when the network is not designed with enough power. This effect, known as voltage flicker, causes unpleasant variations in the light intensity, i.e. flickering, of any lighting installations that are connected to the same mains voltage supply.

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2 Thyristor power controllers 2.1.2

Phase control mode

In phase control mode, the thyristors are fired during each half wave. The fast cycling enables continuous temperature control in extremely fast systems. One example of this is drying of print media with infrared lamps. In addition, this operating mode enables current limiting, which is particularly necessary for heating elements with low cold resistance.

Figure 7:

Current and voltage curves for control of a resistive load in phase control mode

The angle between the zero crossover of the mains voltage and the thyristor firing is called the phase control angle or control angle  el (alpha electrical). When  = 0° el the output is at a maximum, i.e. the mains voltage is applied to the load as complete sine waves. In contrast to this, when  = 180° el there is no voltage drop at the load resistor. The control angle  is varied; in the figure the ratios for  = 45° el are shown: at this point, the thyristors are each fired and the mains voltage is applied to the load. This operating mode is also used in lighting installations, in electroplating, and for transformer loads (operation of low-voltage heating elements via a transformer). Further information about transformer load operation can be found in Chapter 2.2.3 "Burst firing mode with  start", page 15. One drawback of this operating mode is that HF interference is caused by harmonics. The harmonics are produced by the steep rising edge of the cut mains voltage half waves. This generally necessitates the use of interference suppression filters: To prevent radio-frequency interference, electrical apparatus and systems must have interference suppression implemented. The control electronics of the thyristor power controller conform to the EMC requirements of EN 61326. However, modules such as thyristor power controllers have no use by themselves. They only serve as a component function within a plant. Where applicable, the entire load circuit of the power controller must also have suitable interference suppression filters fitted by the plant provider.

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2 Thyristor power controllers Another disadvantage is the generation of reactive power even with a resistive load. This is caused solely by the phase angle control and is therefore referred to as phase control reactive power.

Figure 8:

Explanation of phase control reactive power

Figure 8 a) shows the mains voltage curve and Figure 8 b) shows the mains or load current curve. The current half waves correspond to a fundamental with 50 Hz and harmonics with frequencies in multiples of 50 Hz. The fundamental of the mains current (Figure 8 c)) is shift from the mains voltage by the angle . The current in the mains voltage lags behind the mains voltage, producing reactive power. The phase control reactive power component rises as the control angle increases in size. The operation of large plants necessitates the use of reactive power compensation systems.

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2 Thyristor power controllers 2.2

Combined use of burst firing mode and phase control mode

JUMO thyristor power controllers offer various options for combining burst firing mode and phase control mode. The variations are presented in this chapter.

2.2.1

Soft start

The soft start function is generally used where systems should not be operated with full power immediately when heating up. If the controller causes an output level step from 0 % to the maximum of 100 %, the power controller starts with power of 0 % and increases this over the soft start period up to the required value:

Figure 9:

Heating of the system – controller demands the high output level yR

The soft start helps in the case of heating elements with very low cold resistance. If complete mains voltage full waves were applied, there would be impermissibly high currents in this operating point. In the case of elements with PTC behaviour, the element resistance increases with the temperature. In general, the power controller can also operate in burst firing mode with these elements, but it is then operated with the soft start function via phase control. With the increase in the output level, phase angle control is performed over the soft start time. Due to the large control angle, there are no impermissibly high load currents even when the heating elements are in the cold state. The heating elements are heated during the soft start and the greater element resistance means that the increased load voltage no longer causes impermissibly high load currents. After the soft start, the power controller is in burst firing mode:

Figure 10:

Burst firing mode with soft start through phase control

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2 Thyristor power controllers In Figure 10 the phase control mode is only needed during the cold heating element time. In line with this, the disadvantages of phase control mode only need to be accepted for this period (EMC interference, reactive power etc.). Current limiting can be used during the soft start if necessary. If the set load current limit value is reached, the control angle is not reduced further. The power controller remains in the soft start until the value falls below the limit value. The soft start is also possible with burst firing mode:

U

Clock time

t Figure 11:

Load voltage in burst firing mode for soft start through pulse groups

During the soft start time, the on/off ratio is increased over the cycle time from 0 up to a maximum of 100 %.

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2 Thyristor power controllers Settings for soft start in the configuration program of the TYA thyristor power controller:

Figure 12:

2.2.2

Settings in the configuration program of the TYA thyristor power controller

Switching to phase control mode via binary input

The power controllers can be switched to phase control mode via activation of a binary signal. If necessary, a superordinate controller must perform the switch to phase control mode (for example, if the heating elements are not yet at operating temperature and current limiting is required as a result).

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2 Thyristor power controllers 2.2.3

Burst firing mode with  start

If the nominal voltage of the heating elements does not match the voltage supply, the mains voltage clocked by the thyristor power controller is applied to a transformer. The output voltage of the power controller is transformed to the nominal voltage of the low-voltage heating elements. The power controller current (primary current) is smaller than the heating element current (secondary current) accordingly.

Primary current

L1 230 V AC

Secondary current 60 V AC Furnace

N

Figure 13:

Supply of low-voltage heating elements via a transformer (transformer load)

JUMO thyristor power controllers can operate heating elements via transformers with a nominal induction of 1.2 tesla. Phase control mode is a common operating mode for transformer controls. Where possible, however, you can also make use of the benefits of burst firing mode (no reactive power, low interference potential). Switching at the zero crossover leads to the "rush effect" in transformer loads, whereby the iron in the transformer becomes magnetically saturated, with the result that the primary current is then effectively only limited by the resistive component of the primary winding. The inrush current can be up to 50 times the nominal current here. The rush effect can be counteracted in burst firing mode by cutting the first half wave ( start). For optimum adjustment to the transformer being used, the phase control angle can be set for the first half wave of each pulse burst ( start = 0° el to 90°).

U Load

ωt

α Start Figure 14:

Burst firing mode with  start

The use of a fixed cycle time is recommended for transformer loads.

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2 Thyristor power controllers

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3 Subordinate control loop Voltage supply

w

Controller x

yR

Electrical power controller

y

Path Sensor

Subordinate control loop

Figure 15:

Thyristor power controller with subordinate control loop

The power controllers vary the electrical power in proportion to the output level of the controller (yR) and are themselves subject to fluctuations in mains voltage. Without a subordinate control loop, fluctuations in mains voltage require the intervention of the controller. However, the controller only varies its output level when the process temperature changes. The result is that temporary control deviations occur when the mains voltage changes if there is no subordinate control loop. The subordinate control loop keeps the required power constant even when there are fluctuations in mains voltage. There are three different types of subordinate control loop: • U2 control • I2 control • P control All subordinate control loops have the primary goal of compensating for fluctuations in mains voltage. The subordinate control loops also have a positive effect on the control response. The type of subordinate control loop must be selected according to the heating element used, as well as other factors.

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3 Subordinate control loop 3.1

U2 control

When U2 control is applied, the power controller controls the square of the load voltage in proportion to the required controller output level. When the load resistance is constant, the square of the load voltage is proportional to the power; in this case the power is adjusted: 2

U P = ------R

The U2 control is used with heating elements with a positive temperature coefficient, for example:

Figure 16:

Element with positive temperature coefficient: Resistance and supplied power according to temperature

The resistance of the elements increases as the temperature rises. P = U2 / R shows that with increasing resistance (or rising temperature), the power of the heating element is reduced even if the load voltage remains the same. This effect aids the control loop: If the process temperature increases towards the selected setpoint value, the power supplied to the process decreases (at the same load voltage). Simply selecting the subordinate control loop (here U2) slows the approach to the setpoint value. The principle helps to prevent the temperature from overshooting the setpoint. If the elements are cooled due to a fault, higher power is produced at a lower temperature. The subordinate U2 control loop helps to bring the temperature back up again. If the elements have low cold resistance (Figure 16), the power controller needs current limiting for the heating process.

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3 Subordinate control loop Heating elements with a positive temperature coefficient: • Kanthal Super • Infrared radiators • Tungsten • Molybdenum • Platinum Other applications for U2 control: • In lighting systems: in this case, the intensity of the lighting is proportional to U2. • Resistance materials with a temperature coefficient of around 1; these include heating elements made of nickel/chrome, constantan, etc.

3.2

I2 control

Current control (I2 control) is advantageous for heating elements with a negative TC, where the electrical resistance decreases as the temperature increases.

Figure 17:

Element with negative temperature coefficient: Resistance and supplied power according to temperature

With these elements, the power relationship 2

P = I R

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3 Subordinate control loop also produces the effect described for U2 control. At a constant current, the power is reduced as the temperature increases. Materials with negative temperature coefficients feature non-metals such as graphite or molten glass. In the latter case, the electrical current is fed directly through the molten glass, which converts it into thermal energy. The I2 control is also used where there control of the load current in general. This is the case with electroplating, for example.

3.3

P control

Power control (P control) is a continuous regulation of the product of

P = UI

Typical areas of application include SIC heating elements (silicon carbide) with long-term aging and a simultaneous temperature-dependent change in resistance, see Figure 18.

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4 Dimensioning/operating mode/startup 4.1

Dimensioning

Two variables are key for dimensioning a thyristor power controller: the load current and the load voltage. JUMO supplies power controllers for maximum load currents of 20 to 250 A. The available load voltages are in the range of 24 to 500 V.

4.2

Selecting the power controller properties for the heating element

Common heating elements that are controlled by thyristor power controllers include infrared radiators, molybdenum disilicide heating elements, and SIC heating elements. Low-voltage heating elements are also operated using transformers. This chapter provides information on the required power controller properties. Infrared radiators heat a wide range of materials without contact. As electromagnetic radiation, the heat radiation is as fast as light and the energy is therefore transferred immediately after switch-on. Radiators are classed as short, medium, or long wave depending on the wave length of the emitted radiation. Short-wave radiators have a high hot/cold resistance ratio. This ratio is smaller in the other two radiator types and reaches a value of up to 1. Due to the temperature coefficients of  1, U2 is used as the subordinate control type. The soft start function is often used. Current limiting is needed for short-wave radiators due to the low cold resistance. Molybdenum disilicide heating elements (such as Kanthal Super) have a large positive temperature coefficient. U2 control is used, and current limiting is essential due to the very low cold resistance. The soft start function is often used. The heating elements are highly sensitive to overheating and so the operating temperature is limited with the r-control function; see Chapter 5.3 "Resistance limitation (r-control)", page 27. Silicon carbide heating elements (SIC heating elements) have a negative temperature coefficient at low temperatures and a positive temperature coefficient at high temperatures. P control is used due to this behavior.

Figure 18:

Temperature behavior of an SIC heating element

For effective partial load failure monitoring, the power controller determines the load current in the OK state using the Teach-In function (Chapter 5.2 "Load monitoring", page 25). In order to take aging into account, the Teach-In is repeated every minute for these elements. The aging behavior means that the load voltage must be increased over the lifetime of the heating elements and so SIC JUMO, FAS 620, Issue 2016-01-04

4 Dimensioning/operating mode/startup 21

4 Dimensioning/operating mode/startup heating elements are usually operated via transformers. When heating elements are operated using transformers, both burst firing mode and phase control mode can be used. In burst firing mode, the first half wave is cut with  start. The subordinate control loop and the use of current limiting are based on the connected heating element.

4.3

Connection in single-phase operation: phase/N and phase/phase

Figure 19 shows the general connection of a thyristor power controller, type TYA 201 (simplified wiring diagram).

Figure 19:

Wiring for single-phase mode – phase/N

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4 Dimensioning/operating mode/startup A voltage input and a current input are available for specifying the controller output level. In the example, the current input is used; 0/4 to 20 mA corresponding to 0 to 100 % output level. The control electronics are also supplied with the nominal voltage of the heating elements (load circuit) – no further voltage supply is required. Instead of the L1/N connection, the converter can also be connected between two phases (L1/L2) – a power controller is then used with the correspondingly higher phase-phase voltage. The semiconductor fuse shown (Figure 20) is installed to protect the thyristor module and can be replaced if necessary.

Figure 20:

Semiconductor fuse

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4 Dimensioning/operating mode/startup The table provides an overview for dimensioning the single-phase power controller TYA 201. Connection type

Phase/N

Phase/phase

Rated load voltage for thyristor controller

UN

UL

3~/N/400/230 V

230 V

400 V

Formula for current in thyristor power controller

P total rated/load I S = ---------------------------------UN

P total rated/load I S = ---------------------------------UL

3~/N/400/230 V

IS(A) = 4.35 Ptotal rated/load (kW)

IS(A) = 2.5 Ptotal rated/load (kW)

Formula for maximum power

UN • IS

UL • IS

Pmax with 3~/N/400/230 V 34 kW and IS = 150 A

60 kW

Table 1:

4.3.1

Dimensioning for single-phase power controller

Configuration

The configuration can be performed via the device front or with an easy-to-use setup program. For typical applications, only the following parameters need to be set: Output level signal from controller: Signal type: Operating mode: Subordinate control loop:

Current, voltage 0 to 20 mA, 4 to 20 mA, 0 to 10 V, 2 to 10 V Burst firing mode, phase control mode U2, I2, P

If heating elements with a positive temperature coefficient and a low cold resistance are used (Figure 16), current limiting is used. The maximum permissible current is set.

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5 Functions of the thyristor power controllers TYA 201/202/203 This chapter describes helpful functions of the thyristor power controllers.

5.1

Manual mode

In manual mode, an output level is specified via the device front of the power controller. The controller signal is not included. This function is useful for startup or service work.

Load voltage

Figure 21:

5.2

Load current

Thyristor power controller in manual mode

Load monitoring

Load monitoring monitors several heating elements (connected in parallel or series) for failure or short circuit. Heating elements connected in parallel are monitored via undercurrent monitoring.

» Failure point

Parallel load resistors

Figure 22:

Heating elements connected in parallel

Without monitoring and signaling, the heating power reduces with each broken heating element in the case of subordinate U2 control. In some circumstances, broken elements are not identified by the user. Finally, the plant ceases to function and in an extreme case, another broken heating element may mean that a process cannot be completed. If P or I2 control is used, the power controller attempts to implement the required power (or required current) with the remaining heating elements. The remaining heating elements are heavily loaded and the service life is shortened.

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5 Functions of the thyristor power controllers TYA 201/202/203 A short circuit in heating elements connected in series is detected by overcurrent monitoring.

Figure 23:

Heating elements connected in series

Without monitoring and signaling, the overall power for the plant would be reduced with each shortcircuited heating element in the case of I2 control. With P and U2 control, the power or the load voltage would increase on the remaining heating elements with each short-circuited heating element and the remaining heating elements would be subject to even greater loading. For load monitoring, the correct load ratios and the limit value must be set on the power controller/ converter. The limit value for the power change is determined by the number of elements and the circuit type (single-phase operation, three-phase operation in star or delta connection). The correct load radios can be easily determined for the thyristor power controllers TYA 201/202/ 203 using the "Teach-In" function. After manual "Teach-In" via the device front, the correct load ratios of the plant are stored. Based on this state, the load changes are continuously monitored independently of the required output level. In the event of a failure or short circuit of a heating element, the load current increases or decreases. This is detected by the load monitoring and a load fault is signaled.

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5 Functions of the thyristor power controllers TYA 201/202/203 5.3

Resistance limitation (r-control)

This function limits the delivered power according to the temperature of molybdenum disilicide heating elements and prevents them from overheating.

Figure 24:

Resistance of a molybdenum disilicide heating element according to the element temperature

For this function, the load resistance that is present at the maximum permissible temperature on the element is entered on the power controller. When the set load resistance is reached, the power controller reduces the supplied power and the heating element is protected against overheating.

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5 Functions of the thyristor power controllers TYA 201/202/203 5.4

Firing pulse inhibit

The binary input for firing pulse inhibit deenergizes the power controller output. To ensure that there is no voltage present, there generally needs to be a circuit breaker or main switch upstream of the power controller as otherwise a minimal off-state current flows through the semiconductor components.

5.5

Dual energy management

Dual energy management reduces the current peaks in the system at an overall output level of up to 100 %. The reduction is also made with unsymmetrical distribution of the output levels, for example 30 % and 70 %. This can be explained using two power controllers as an example (power controller 1 and power controller 2). Power controller 1 works with an output level of 20 % (for example 2 kW); power controller 2 requires an output level of 60 % (for example 6 kW). Each power controller operates an element with a nominal power of 10 kW.

Unit 1

Furnace

Power required: 2 kW Nominal power: 10 kW

Furnace

Power required: 6 kW Nominal power: 10 kW

L1 230 V AC N Unit 2

L1 230 V AC N Figure 25:

Reduced current peaks when using dual energy management and a total output level of  100 %

The two plants require an average total power of 8 kW. If the power controllers switch the mains voltage to the load at the same time, power of 20 kW is taken from the mains voltage. If at least two power controller are operating, the devices are split into groups of two. In each group, one TYA power controller must be configured as device 1 and the other TYA power controller must be configured as device 2. The devices must be connected to the same phase and operate in burst firing mode with a fixed cycle time of 500 ms.

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5 Functions of the thyristor power controllers TYA 201/202/203

Figure 26:

Mains current with dual energy management

The two power controllers switch on at different times. Starting from the dashed lines, the energy is dispersed symmetrically to the left and right (see arrows). Provided that the total output level of the two devices is 100 % or below, overlaps of the two device currents in a single phase are prevented (mains current = IThy1 or IThy2). Current peaks only occur when the output level exceeds 100 % (power current = IThy1 + IThy2). With energy management, up to 10 kW is taken from the mains voltage in the example. Without energy management this would be up to 20 kW.

5.6

Monitoring of the mains voltage drop

Mains voltage drop monitoring is used with transformer loads and monitors the mains voltage for symmetry. A direct component in the primary winding of the transformer leads to a high load current and destroys the semiconductor fuse of the thyristor power controller once a certain value is reached. If the effective values of the analyzed half waves differ by more than 10 %, an alarm message is displayed and the binary output for the collective alarm switches. The immediate firing pulse inhibit prevents destruction of the semiconductor fuse. If there are no further mains voltage drops, the firing pulse inhibit is removed and the power controller continues operation (e.g. with a soft start).

5.7

Half-wave control for vibration drives

In production processes, vibration is used to clear product jams, prevent blockages, or drive feeders. The electrical vibration drives needed for this are activated by the thyristor power controller in half-wave control. The intensity of the vibration can be controlled by varying the control angle .

JUMO, FAS 620, Issue 2016-01-04

5 Functions of the thyristor power controllers TYA 201/202/203 29

5 Functions of the thyristor power controllers TYA 201/202/203 5.8

Connection via interfaces

Power controllers from the series TYA 201/202/203 can be connected at any time using analog or binary signals. The following are available: • One current input and one voltage input for specifying the output level • One universal output (0/4 to 20 mA, 0/2 to 10 V) for signaling, for example the power • Three binary inputs for activating various functions • One relay output for reporting faults Various interfaces are available for connecting the power controllers to a master system. Examples of master systems include: • Process control systems • Visualization software products • Programmable logic controllers The interfaces are used for retrieval of the relevant process variables by the master system or to control the power controller (for example, specifying the output level). Serial interfaces (RS485 and RS422) provide the hardware for data transfer. Modbus RTU is used as the transfer protocol. The RS485 interface is normally used in conjunction with process visualization software, with a control system, or for communication between field devices. A two-wire line connects up to 32 stations to each other of a distance of 1200 m.

Figure 27:

Communication between a DICON touch two-channel process and program controller and two thyristor power controllers

The RS485 interface of the two-channel process controller in Figure 27 operates as the Modbus master interface. The interface is used to transfer output levels to the power controllers, for exam-

30 5 Functions of the thyristor power controllers TYA 201/202/203

JUMO, FAS 620, Issue 2016-01-04

5 Functions of the thyristor power controllers TYA 201/202/203 ple. The RS422 interface offers very similar options, but uses two cable pairs for data transfer. Field devices are normally connected to a PLC via PROFIBUS-DP. The PLC exchanges all the necessary process variables with the field devices. The GSD file for the relevant field device is needed to set up communication. Once this file has been imported into the configuration software of the PLC, the field device is available in the software. The GSD file is used to define the process variables to be transferred. JUMO provides the GSD Generator for creating the file:

Figure 28:

GSD Generator for creating the GSD file

The GSD Generator offers a wide range of variables. For each application, the parameters are selected that are to be transferred from the power controller to the PLC (PLC input) or from the PLC to the field devices (PLC output).

JUMO, FAS 620, Issue 2016-01-04

5 Functions of the thyristor power controllers TYA 201/202/203 31

5 Functions of the thyristor power controllers TYA 201/202/203

32 5 Functions of the thyristor power controllers TYA 201/202/203

JUMO, FAS 620, Issue 2016-01-04

6 Thyristor power controllers in a three-phase system This chapter provides information on using the power controllers for three-phase systems (TYA 202 and TYA 203). The following figure provides an introductory explanation of the characteristics in a three-phase network:

IL L1 UL L2

L3 UN N

IS

I Load

Figure 29:

Characteristics of a three-phase network

UN

:

Phase voltage (voltage between the phase and neutral conductors)

UL

:

Phase-phase voltage (voltage between two phase conductors)

IL

:

Current in the phase conductor

IS

:

Current through the power controller

ILoad :

Load current

Note: In a three-phase network 3~/N/400/230 V, the phase-phase voltage is 400 V and the phase voltage is 230 V.

JUMO, FAS 620, Issue 2016-01-04

6 Thyristor power controllers in a three-phase system 33

6 Thyristor power controllers in a three-phase system 6.1

JUMO TYA 202 – thyristor power controller for controlling ohmic-inductive loads in three-phase economy circuits

The TYA 202 switches two phases and therefore operates loads in the three-phase system without a neutral point. The load (star or delta) is operated on phase 1 and 3, in each case via a thyristor. Phase 2 is connected directly to the load (Figure 31). Regardless of whether the load is connected in a star or a delta configuration, the thyristor power controllers must be dimensioned for the phase-phase voltage. Burst firing mode is used, and soft start is also possible for transformer loads. The power controller operates with the master-slave principle. The master controls the system and synchronizes the slave. The two components are connected via a patch cable. The configuration is carried out via the device front of the master or via its USB interface.

Figure 30:

JUMO TYA 202 – thyristor power controller for controlling ohmic-inductive loads in three-phase economy circuits

34 6 Thyristor power controllers in a three-phase system

JUMO, FAS 620, Issue 2016-01-04

Setpoint input:

+

1 2 3 4 5 6

0(4) to 20mA

1 2 3 4 5 6

Ohmic load in a star connection

7 8 9 10 11 12

7 8 9 10 11 12 1

1

Patch cable 8

8

Optocoupler C

Ö

E

13 14 15

13 14 15

Relay

P

S

Ohmic load in a delta connection

Semiconductorfuse

UThy = UL

N/L2 V

L1

U2 U1

Semiconductorfuse

N/L2 V

P P IThy = tot = tot 3 · UN 3 · UL

L1

U2 U1

Fuse for control electronics 2A up to a maximum of 5 A

Fusing to protect the power section cabling

6 Thyristor power controllers in a three-phase system

UL UN

IL

Transformer load IThy = IL in a star connection

IThy

Figure 31:

Connection of the TYA 202 in three-phase economy circuit in star or delta configuration

The power controller current is calculated as follows:

P tot P tot I Thy = ---------------= ------------------3  UN 3  UL The formula applies for connection of the loads in star or delta connections with symmetrical load distribution.

JUMO, FAS 620, Issue 2016-01-04

6 Thyristor power controllers in a three-phase system 35

6 Thyristor power controllers in a three-phase system 6.2

JUMO TYA 203 – three-phase thyristor power controller

The three-phase thyristor power controller also has a master, but uses this and two slaves to switch all three phases in the three-phase system. Patch cables are also used here for the connection between the master and slaves.

Figure 32:

JUMO TYA 203 – three-phase thyristor power controller

36 6 Thyristor power controllers in a three-phase system

JUMO, FAS 620, Issue 2016-01-04

6 Thyristor power controllers in a three-phase system The three-wire connection is the same as for TYA 202, but three phases are switched:

Figure 33:

Connection of the TYA 203 in star or delta connection (three-wire circuit), if necessary with N conductor in star connection (four-wire circuit)

Switching of three phases means that phase control mode is possible with the power controller in addition to burst firing mode. The power controllers must be dimensioned for the phase-phase voltage. The formula for the power controller current is the same as for the three-phase economy circuit:

P tot P tot = ------------------I Thy = ---------------3  UN 3  UL The formula applies for connection of the loads in star or delta connections with symmetrical load distribution. Open delta connection can be used if the two connections of each load are available for electrical connection. The circuit type is also known as a six-wire circuit:

JUMO, FAS 620, Issue 2016-01-04

6 Thyristor power controllers in a three-phase system 37

6 Thyristor power controllers in a three-phase system

Figure 34:

Connection of the TYA 203 in open delta connection

The power controllers must be dimensioned for the phase-phase voltage. The power controller current is lower than that in the three-wire circuit and with symmetrical load distribution is:

P tot P tot I Thy = --------------- = -------------------3  UL 3  UN

38 6 Thyristor power controllers in a three-phase system

JUMO, FAS 620, Issue 2016-01-04

6 Thyristor power controllers in a three-phase system The table provides an overview for dimensioning the power controllers in the three-phase system TYA 202/203: Star/delta economy circuit three-wire circuita

Four-wire circuita

Six-wire circuita

JUMO power controller

TYA 202 or TYA 203

TYA 203

TYA 203

Rated load voltage for thyristor controller

UL

UL

UL

3~/N/400/230 V

400 V

400 V

400 V

Formula for current in thyristor power controller

P total rated/load I S = ---------------------------------3  UN

P total rated/load I S = ---------------------------------3  UL

3~/N/400/230 V

IS(A) = 1.45 Ptotal rated/load (kW)

IS(A) = 0.83 Ptotal rated/load (kW)

Formula for maximum power

3 • UN • IS

3 • UL • IS

Pmax with 3~/N/400/230 V 103 kW and IS = 150 A a

180 kW

With symmetrical load distribution

Table 2:

Dimensioning of thyristor power controllers in a three-phase system

JUMO, FAS 620, Issue 2016-01-04

6 Thyristor power controllers in a three-phase system 39

6 Thyristor power controllers in a three-phase system

40 6 Thyristor power controllers in a three-phase system

JUMO, FAS 620, Issue 2016-01-04

7 Reference list [1]

F. Blasinger, Thyristorsteller: Das perfekte Stellorgan für elektrische Heizungen; elektrowärme international 50 (1992) B3

[2]

K. Heumann, Grundlagen der Leistungselektronik; Teubner 1989

[3]

M. Burmeister, Thyristor-Steller: Technik und Anwendung; Firmenschrift der JUMO GmbH & Co. KG, Fulda, 1990

[4]

K. Heumann, C. Stumpe, Thyristoren: Eigenschaften und Anwendungen; Teubner 1974

[5]

W. Keuter, Das Stellen und Schalten von Wechselgrößen; Hüthig-Verlag 1982

JUMO, FAS 620, Issue 2015-05-18

7 Reference list 41

7 Reference list

42 7 Reference list

JUMO, FAS 620, Issue 2015-05-18

Informative material from JUMO – for beginners and those with some practical experience Know-how is not just needed to create JUMO products, but also for their later application. That is why we offer several publications on aspects of measurement and control engineering for our users. The publications are intended to provide step-by-step familiarization with a wide range of applications, for both beginners and those with some practical experience. They primarily illustrate general topics with JUMO-specific applications to some extent. In addition to JUMO technical literature and our new software downloads we also offer the possibility to order our brochures and CD-ROM catalogs online. Electrical Temperature Measurement

Control Engineering

with thermocouples and resistance thermometers Matthias Nau

Basic principles and tips for practitioners Manfred Schleicher

FAS 146 Sales no.: 00085081 ISBN: 978-3-935742-07-X Free of charge

FAS 525 Sales no.: 00323761 ISBN: 978-935742-01-6 Free of charge

Explosion Protection in Europe

Information on high-purity water

Electrical equipment fundamentals, guidelines, standards Jürgen Kuhlmei

Reinhard Manns

FAS 547 Sales no.: 000414312 ISBN: 978-3-935742-10-X Free of charge

FAS 614 Sales no.: 00403834 Free of charge

Information on redox voltage measurement

Information on the amperometric measurement of free chlorine, chlorine dioxide and ozone in water

Ulrich Braun

Dr. Jürgen Schleicher FAS 615 Sales no.: 00398237 Free of charge

FAS 619 Sales no.: 00398147 Free of charge

SCR Power Controllers

Information on pH measurement

Basic principles and tips for professionals Manfred Schleicher, Winfried Schneider FAS 620 Sales no.: 00400481 ISBN: 978-3-935742-05-4 Free of charge

Matthias Kremer FAS 622 Sales no.: 00403233 Free of charge

Informative material from JUMO – for beginners and those with some practical experience Information on Conductivity Measurement

Error Analysis of a Temperature Measurement System

Reinhard Manns

with worked examples Gerd Scheller, Stefan Krummeck

FAS 624 Sales no.: 00411341 Free of charge

FAS 625 Sales no.: 00415704 ISBN-13: 978-3-935742-13-4 Free of charge

Information on the Measurement of Hydrogen Peroxide and Peracetic Acid

Functional Safety Safety Integrity Level Dr. Thomas Reus, Matthias Garbsch

Dr. Jürgen Schleicher FAS 628 Sales no.: 00420697 Free of charge

FAS 630 Sales no.: 00476107 Free of charge

Information on measuring ammonia in water Dr. Jürgen Schleicher FAS 631 Sales no.: 00485097 Free of charge

Please visit our website www.jumo.net and familiarize yourselves with the wide variety of JUMO products for different application fields. Our website provides you with more details and information concerning the contact persons for your requirements, questions, and orders.

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