Resistive Capacitive Voltage Dividers for Gas Insulated Switchgear

Introduction Power quality has become a major concern, both for electricity providers and their customers. As today’s electrical equipment is far more sensitive than electrical devices of the past, a reliable picture of the HV line voltage is needed to determine the origin of power disturbances.

RC Voltage Divider High Voltage Terminal

R13

Harmonics measurements Unlike capacitive voltage transformers (accuracy on narrow frequency band only) and inductive voltage transformers (harmonic frequency resonances between winding inductances and stray capacitances), RC Voltage Dividers are linear from DC up to 20 kHz. Harmonics can be measured with an accuracy better than 1 % (see Fig. 2) and a phase displacement less than 1° on this frequency range.

Ratio Error [%]

Both for power quality measurements and for measurements at rated frequency, Trench Resistive Capacitive Voltage Dividers (RC Voltage Dividers) are able to measure over a large frequency band with a high accuracy. They are an effective solution for a modern SMART Grid infrastructure.

Measurements at rated frequency Trench RC Voltage Dividers cover all IEC and ANSI metering requirements (class 0.2 or lower). They can also be used for protection purposes according IEC or ANSI.

C11

1

-2

1a

F

2

-1

-3

1n

C22

3

0

External Burden Coaxial Cable

R24

4

Ck

Rk

Ground Terminal

-4

CB

1

10

100

10.000

1.000

100.000 1.000.000 Frequency [Hz]

Fig. 2: Magnitude versus frequency test over the entire bandwidth

R13:

Primary Resistance

R24:

Secondary Resistance

F:

Spark Gap

RB:

Load Resistance

C11:

Primary Capacitance

C22:

Secondary Capacitance

Ck:

Stray Capacitance

C B

Burden Capacitance

Ratio Error [%]

Fig. 1: Equivalent Circuit Diagram of an RC Voltage Divider 500 400 Capacitive Voltage Transformer 420 kV

300 200

Inductive Voltage Transformer 420 kV RC Voltage Divider 420 kV

100 0

0

500

1000

1500

2000

2500

Frequency [Hz]

Fig. 3: Bandwidth comparison of an Inductive Voltage Transformer, a CVT and an RCVD

2

Fig. 4: RCVD 145T

Fig. 5: RCVD 420

Design Trench RC Voltage Dividers are designed based on the long experience with capacitive dividers and capacitors for different applications (capacitive voltage transformers, coupling capacitors, dividers for DC applications or test labs, energy storage capacitors or grading capacitors). The resistors connected in parallel to the capacitor windings are designed to guarantee an extremely low resistance variation through time, electrical stress and temperature. The insulation system is made of oil / paper-polypropylene mounted in a composite housing. The whole design is directly mounted into the GIS in the common SF6-gas compartment. Trench RC Voltage Dividers are designed to allow an easy and fast customization to specific customer requirements.

Features • Available for voltage levels 72.5 kV – 145 kV (three-phase design) and 245 kV – 550 kV (single-phase design) • Accurate from DC up to 20 kHz • Bandwidth up to 2 MHz • Ferroresonance-free (no saturable cores) • Excellent transient characteristics • Conform to microprocessor-based secondary technology • Short-circuit proof design • Disconnection during commissioning tests on site not necessary, e.g. in case of DC-tests (cable tests) • Significant size and weight reduction

3

Technical Data

RCVD 145T

3-Phase Units Type

RCVD 72T

RCVD 123T

RCVD 145T

Um

[kV]

72.5

123

145

AC

[kV]

140

230

275

BIL

[kV]

325

550

650

SIL

[kV]

-

-

-

Output voltage

[V]

As required (typically 100/√3)

Rated voltage factor Accuracy range

1.5 or 1.9 [kHz]

0 – 20

Rated burden

1 MΩ + 500 pF

Metering class

according to IEC or ANSI

Protection class Temperature range

[°C]

-30 – +55

Insulation class

E

Weight

[kg]

90

90

90

Height

[mm]

770

770

770

Min. field distance

[mm]

575

575

575

4

RCVD 245

RCVD 300 – 420

RCVD 420 – 550

Single-Phase Units Type

RCVD 245

RCVD 300

RCVD 362

RCVD 420

RCVD 550

Um

[kV]

245

300

362

420

550

AC

[kV]

460

460

510

630

680

BIL

[kV]

1050

1050

1175

1425

1550

SIL

[kV]

-

850

950

1050

1175

Output voltage

[V]

As required (typically 100/√3)

Rated voltage factor Accuracy range

1.5 or 1.9 [kHz]

0 – 20

Rated burden

1 MΩ + 500 pF

Metering class

according to IEC or ANSI

Protection class Temperature range

[°C]

-30 – +55

Insulation class

E

Weight

[kg]

110

160

160

Height

[mm]

1257

1852

1852

Min. phase distance

[mm]

400

490

490

1601) 2602) 18521) 15222) 4901) 6462) 1) 2)

260 1522 646

Design RCVD 300 – 420 Design RCVD 420 – 550

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Trench Factories Trench Austria GmbH Paschinger Strasse 49 Postfach 13 A-4060 Linz-Leonding Austria Phone: +43-732-6793-0 Fax: +43-732-671341 Trench Brasil Ltda Via Expressa de Contagem, 2685 Contagem, Minas Gerais CEP 32370-485 Brazil Phone: +55-31-3391-5959 Fax: +55-31-3391-1828 Trench China MWB (Shanghai) Co., Ltd. No. 3658, Jiancheng Road Minhang, Shanghai P. R. China 200245 Phone: +86-21-54720088 Fax: +86-21-54723118

Trench High Voltage Products Ltd., Shenyang No. 2 Zhengliang Er. Road Jing Shen Xi San Street Dao Yi Economic Development Zone Shenyang 110136 P. R. China Phone: +86-24-89722688 Fax: +86-24-289737200 Trench Italia S.r.l. Strada Curagnata, 37 IT-17014 Bragno Cairo, Montenotte (SV) Italy Phone; +39-019-5161-111 Fax: +39-019-5161-401 Trench Limited Bushing Division 432 Monarch Avenue Ajax, Ontario Canada L1S 2G7 Phone: +1-905-426-2665 Fax: +1-905-426-2671

Trench France S.A. 16, Rue du Général Cassagnou B.P. 70 F-68 302 St. Louis, Cedex France Phone : +33-3-89-70-2323 Fax : +33-3-89-67-2663

Trench Limited Coil Products Division 71 Maybrook Drive Scarborough, Ontario Canada M1V 4B6 Phone: +1-416-298-8108 Fax: +1-416-298-2209

Trench Germany GmbH Nürnberger Strasse 199 D-96050 Bamberg Germany Phone: +49-951-1803-0 Fax: +49-951-1803-224

Trench Limited Instrument Transformer Division 390 Midwest Road Scarborough, Ontario Canada M1P 3B5 Phone: +1-416-751-8570 Fax: +1-416-751-6952

The Trench Group is your partner of choice for electrical power transmission and distribution solutions today and for the development of your new technology solutions of tomorrow.

Trench Limited Power Line Carrier Division 330 Finchdene Square Scarborough, Ontario Canada M1X 1A5 Phone: +1-416-847-5400 Fax: +1-416-291-5581