CDG 11 CDG 16

GEC Measurements

Types CDG 11 & 16 The type CDG11 relay is a heavily damped induction disc unit with an inverse definite minimum time/current characteristic. The relay gives selective phase and earth fault overcurrent protection in time graded systems to transformers, a.c. machines and feeders, etc., and ensures that a minimum number of circuit breakers are tripped to clear a faulted section (see Application Sheet MS/5087). The operating coil is wound to give time/current curves of the same shape on each of seven current taps which are selected by a plug setting bridge. The highest current tap is automatically selected when the plug is removed, so that adjustments can be made on load without open-circuiting the current transformer. The relay has a high torque movement to ensure consistent timing even under adverse conditions, and a low burden and overshoot. Adjustment of the time setting is made by rotating a knurled moulded disc against a graduated time multiplier scale. A high set overcurrent unit (type CAG) can be fitted in the same case to provide instantaneous protection under maximum short circuit conditions (see Application Sheet MS/5087). The type CDG21 relay is either a double pole version (with two earth fault units or two over-current units) of the type CDG11, or a type CDG11 with an instantaneous unit. The type CDG31 relay is a triple pole version (with three overcurrent units or two overcurrent units and one earth fault unit in the centre) of the type CDG11.

CURRENT SETTINGS Equally Spaced Tap Ranges 10-40%, 20-80% or 50-200%, of 0-5, 10 or 5 0 amps 50 or 60Hz adjustable in seven equal steps.

Graded Tap Ranges 10-40%, 20-80%. or 50-200% of 0-5, 10 or 5 0 amps and 30-120% or 80-320% of 5 amp 50 or 60Hz adjustable in seven unequal steps as follows 25%, 30%, 37-5%, 50%, 60%, 75% and 100% of top tap value.

Starting Current 103-105% of current set-ting

Type CDG 11 relay

Closing Current 115% of current setting (117% when fitted with a mechanical operation indicator)

Resetting Current The maximum current up to which the disc will completely reset is 90% of current setting.

T I M E SETTINGS 0-1-3 seconds at 10 times current setting or 0 -3 0 seconds at 10 times current setting (B.S.142:1966)

Resetting Time With the time multiplier set at 1 0 the resetting times of the above are four seconds and nine seconds respectively. Overshoot On removal of a current equal to 20 times current setting the overshoot times of the above are 0 065 second and 0 04 second respectively.

BURDENS Standard (3VA nominal)—

2VA at current setting on lowest tap 3-5VA at current setting on highest tap

Alternative with lower operating torque (1VA nominal)—

0-75VA at current setting on lowest tap 1-3VA at current setting on highest tap

THERMAL RATING The relay will withstand twice the setting current continuously and 20 times the maximum setting current for three seconds.

ACCURACY The relay is calibrated at 50 Hz and 20°C and falls into error class index E7-5 as given in B.S. 142:1966. Frequency Error Less than 8% for frequency variation of 2 cycles; the time grading of a pro-tective system would be unaffected by this error since all the relays would be similarly affected.

MULTIPLES OF PLUG SETTING CURRENT

Curve reference 398.S23.15

Temperature Error For an overload equal to ten times the current setting, the percentage timing errors at +45°C and —5°C are res-pectively:—

1-3 second relay —4% and + 4 % 3 0 second relay —3% and + 4 %

AUXIL IARY UNITS AND OPERATION INDICATORS Shunt reinforcing or series seal in auxiliary attracted armature units with a hand reset operation indicator can be fitted. Relays supplied without an auxiliary unit have a hand reset operation indicator mechanically operated by the disc. Standard Coil Ratings Voltage operated (shunt) auxiliary units: 30, 110, 125 or 220 volts d.c. at a nominal burden of 3 watts continuously rated.

Curve reference S77398Z06.017

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0-8

0-7

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2-5-10 AMP 1 VA 50 CYCLE MULTI-STRAND COIL 2-5-10 AMP 1 VA 50 CYCLE MULTI-STRAND COIL \ 25 AMP TAP \ 25 AMP TAP

/ 3-75 „ 5-0 .. 6-25 .. 7-5 .. 8-75 .. 100 ..

3-75 „ 5-0 .. 6-25 .. 7-5 .. 8-75 .. 100 ..

\ 3-75 „ 5-0 .. 6-25 .. 7-5 .. 8-75 .. 100 ..

\ /

3-75 „ 5-0 .. 6-25 .. 7-5 .. 8-75 .. 100 .. /

3-75 „ 5-0 .. 6-25 .. 7-5 .. 8-75 .. 100 .. V / / /

3-75 „ 5-0 .. 6-25 .. 7-5 .. 8-75 .. 100 .. \ / / /

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2 4 6 8 10 12 14

MULTIPLES OF PLUG SETTING C U R R E N T

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2-5 AMP. TAP 3-75 .. \ 5-0 625 7-5 8-75 10 0

\ 5-0 625 7-5 8-75 10 0

5-0 625 7-5 8-75 10 0

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MULTIPLES OF PLUG SETTING C U R R E N T

Current operated (series) auxiliary units:

Minimum operating

current in amps (two taps)

0-5 second current

rating in amps

Coil resistance in ohms

0-1 and 0-3 0-2 and 2 0 0-6 and 2-4

18 and 22 22 and 92 92 and 188

9-2 and 2-1 6-0 and 0-125 0-29 and 0-031

Other coil ratings can be supplied for both types of auxiliary unit.

Contacts One or two electrically separate normally-open self or hand reset contacts are fitted which will make and carry 7500VA for 0-5 second with maxima of 30 amps and 660 volts a.c. ord.c.

Relays supplied without an auxiliary unit have one or two pairs of normally-open self reset contacts which will make and carry 2500VA for 0-5 second with maxima of 10 amps and 660 volts a.c. or d.c. The two contact relay has a modified disc/contact assembly and is designated CDG16, CDG26 or CDG36.

A.C. Trip Circuit Where a tripping supply is not available, a modified relay can be supplied which trips the circuit breaker directly using current from the line transformer. The a.c. trip-ping circuit incorporates a current transformer and an instantaneous unit which will safely control a.c. trip coil currents up to 150 amps at 150 volts. Applications where the trip current exceeds this value can also be catered for.

CASES The relays are supplied in drawout cases available for flush or projecting mounting, and finished in phenolic black as standard. These cases offer many advantages including ease of maintenance and testing, and are fitted with a contact which short circuits the associated current transformer

on withdrawal of the unit. A filter is fitted which equalises the pressure inside and outside the case without admitting dust.

Relays for use in exceptionally severe environ-ments can be finished to B.S.2011:20/50/56 at extra cost; standard relays are finished to B.S.2011:20/40/4 and are satisfactory for normal tropical use.

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(NSTAIMTANEOUS UNIT

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COIL | I

-O jUUU— INTERNAL C.T.

PLUGBOARD

TRIP COIL

- ( • — RELAY CASE T E R M I N A L

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— o o — N O R M A L L Y OPEN CONTACT

Connection diagram for a.c. series tripping

CASE D I M E N S I O N S

Relay Case

Maximum Overall Dimensions

Relay Case Height Width Depth' Relay Case

in. mm in. mm in. mm

CDG11 CDG21 1 D 233 6 U 170 73 197

CDG21 (double pole)

2D (Vert.)

16» 422 6 H 170 7 1 197

CDG31

3D (Vert.)

2 0 f 524 6 H 170 73 197

CDG31

3D (Horiz.)

9i 235 1 7 | 454 73 197

Dimensioned draw-ings of case out-lines, panel cut-outs and mounting details are available on request.

"Add 2 in. (51 mm) for maximum length of 2 BA terminal studs.

-PPt

. SHORTING X T l T CONTACTS

NOTE ALLTHREE ELEMENTS ARE THE SAME AND ONLY ONE IS SHOWN. ALARM AND TRIPCCTS ARE PARALLELED

THREE PHASE OVERCURRENT PROTECTION

EARTHING ARRANGEMENTS Although not included in the diagram, it is assumed that secondary C.T. and/or V.T. circuits will be earthed as necessary in compliance with standard safety requirements and determined by the switchgear contractor or user. If in doubt, please consult GEC Measurements for advice.

INSULATION The relay will withstand 2-0 kV r.m.s. a.c. 50 Hz for 1 minute between all live parts and earth and between all circuits not intended to be connected together. It will also withstand 1 kV r.m.s. a.c. 50 Hz for 1 minute across open contacts.

PR

C.T. CONNECTIONS FOR OVERCURRENT AND EARTH FAULT PROTECTION

m

5 X ^ vi!/ ^ t T i

m

9

O/C

Typical application and internal circuit diagram of type CDG31 relay with series seal in

I N F O R M A T I O N REQUIRED W I T H ORDER Relay type Current setting range Current transformer secondary rating Characteristic (time setting) Burden Trip circuit (series seal in, shunt rein-

forcing or a.c.) Trip circuit current (series seal in) Trip circuit voltage (shunt reinforcing) Operation indicator inscription if required Auxiliary contacts (hand or self reset) Details of instantaneous unit (CAG) if

required Case mounting

Our policy is one of continuous product development and the right is reserved to supply equipment which may vary slightly from that described.

GEC Measurements The General Electric Company Limited of England

St. Leonards Works Stafford ST17 4LX England Telephone: 0785 3251 Telex: 36240 Cables: Measurements Stafford Telex

Publication R-5090D 097960GSP Printed in England