Type CDG 21/61

IDMT Overcurrent and Earth Fault Relay with Highset

Type CDG 21/61Type CDG 21/61IDMT IDMT OvercurrentOvercurrent and Earthfault Relay with high-set instantaneous unit. and Earthfault Relay with high-set instantaneous unit.

FeaturesFeatures

Identical time/ currentcharacteristics on all taps.

Self-powered, no necessityfor separate auxiliarysupply.

High torque, ensuringconsistent timing evenunder adverse conditions.

Very low overshoot. Simple construction, easily

accessible. Comprehensive range of

high-set unit ratings. Dustproof drawout case

and tropicalised finish.

ApplicationApplication

Selective phase and earthfaultprotection, in time gradedsystems for AC machines,transformers, feeders etc.

General descriptionGeneral description

A non-directional heavilydamped induction disc relay,which has an adjustableinverse time/currentcharacteristic with a definiteminimum time. CDG 21andCDG 61 are 1 & 3 poleversions of CDG11 withhighset instantaneous unitrespectively. The relay has ahigh torque movementcombined with low burdenand low overshoot. The relaydisc is so shaped that as itrotates the driving torqueincreases and offsets thechanging restraining torqueof the control spring. Thisfeature combined with thehigh torque of the relay

ensures good contact pressureeven at currents near pick-up.

Damping of the discmovement is by a removablehigh retentivity permanentmagnet. The unique methodof winding the operating coilensures that the time/currentcharacteristics are identical oneach of the seven currenttaps. Selection of the requiredcurrent setting is by means ofa plug setting bridge, whichhas a single insulated plug.The maximum current tap isautomatically connected whenthe plug is withdrawn fromthe bridge, allowing thesetting to be changed underload without risk of opencircuiting the currenttransformers. The IDMT relayhas an auxiliary unit which ispowered by a secondarywinding on the electromagnetthrough a rectifier and assuch a separate auxiliarysupply is not required. Thedisc unit operates and closesits contacts, the auxiliaryelement connected across thesecondary winding on theelectromagnet operates andone normally open contact ofthe auxiliary elementreinforces the disc contact.Two other contacts of theauxiliary element are broughtout to the terminals of therelay.

The relay operating time canbe adjusted by movement ofthe disc backstop which iscontrolled by rotating aknurled moulded disc at the

base of the graduated timemultiplier scale. A high-setinstantaneous overcurrent/earth fault unit is fitted in thesame case to provideinstantaneous protectionunder maximum short circuitconditions and to improvediscrimination on time gradedprotective systems

Technical dataTechnical data

Current ratingsCurrent ratings1A or 5A.

IDMT settingsIDMT settings 50 - 200% in seven equal

steps of 25%. 20 - 80% in seven equal

steps of 10%. 10 - 40% in seven equal

steps of 5%. Other setting ranges

available on request.

Starting currentStarting current103 - 105% of current setting.

Closing currentClosing currentNot more than 130% ofcurrent setting.

Instantaneous highsetInstantaneous highsetsettingssettings E/F 100 - 400%, O/C 400 - 1600% Other setting ranges

available on requests For special applications

highest unit with lowtransient overreach is alsoavailable as option.Please contact ourapplication departmentfor details.

Time settingsTime settingsOperating timeOperating time0 - 3 seconds or0 - 1.3 seconds at 10 timescurrent setting.

Resetting timeResetting time4 seconds for 1.3 secondsrelay and 9 seconds for 3seconds relay with timemultiplier setting at 1.0

OvershootOvershootOvershoot time on removal of20 times setting current. Less than 0.065 second

for 1.3 seconds relay Less than 0.04 second for

3 seconds relay.

Thermal ratingThermal rating Maximum continuous

current rating for 60Crise in coil temperature.

OperatingCoil tap

1 2 3 4 5 6 7

Timescurrentsetting

4.5 3.7 3.2 2.7 2.6 2.4 2.2

Withstand 20 timesmaximum setting currentfor 3 seconds.

AccuracyAccuracyError class indexE7.5 as per BS 142-19667.5 as per IS 3231-1965

Frequency errorFrequency errorTiming error less than 8% for2 Hz frequency variations.

Time grading unaffected bysuch small error, since allrelays are similarly affected.

Temperature errorTemperature errorFor 10 times setting current,at ambient temperaturebetween+45C and 5C,percentage timing errors areas follows: 3 seconds relay: 3%

and +4% 1.3 seconds relay: 4%

and +4%.

Auxiliary units and operationAuxiliary units and operationindicatorsindicatorsSelf-powered auxiliary unitwill have following contactcombinations:

1. S/R - 2N/O or2. H/R - 2N/O + 2 N/C.

Contact ratings auxiliary unitContact ratings auxiliary unitcontactcontactMake and carry for 0.5second 7500 VA with maximaof 30 amps/ 660 volts ac/dc.

InsulationInsulationThe relay meets therequirements ofIS 3231-1965/IEC.265-6series C-2 kV for 1 minute.

BurdenBurden3VA nominal2VA on the lowest tap3.5VA on high-set tap.

Case and finishCase and finish1D vertical or 3D vertical,horizontal case suitable forflush or projection mountingand finished eggshell blackand tropicalised. Suitable tripisolating switch and CTshorting switches provided onthe cradle

Information required withInformation required withOrderOrder

1. Current transformersecondary rating.2. Current setting range.3. Characteristic (0 - 3.0 sec.or 0 - 1.3 sec. at 10 timescurrent setting).4. Operation indicatorinscription, if required.5. Auxiliary contacts - hand orself reset.6. Current setting range ofhigh-set unit, if required.7. Case size.8. Type of mounting - flush or projection.

Dimensions and weightsDimensions and weights

Maximum overall dimensionsRelay Casesize Height

mmWidthmm

Depth*mm

Approximategross weight

Kg.CDG 21 1D Vert. 233 170 203 6.0

3D Horz. 233 454 203 15.5CDG 613D Vert. 524 170 203 15.0

* Add 76 mm for maximum length of terminal studs, alternatively, 29 mm for terminal screws.The approximate gross weights given above are inclusive of cartons, mounting appendages and terminal details.The relays comply fully with the requirements of IS 3231-1965 and are suitable for use in normal tropical environments.

PR:084:0502:A Printed in India.

ALSTOM Limited Pallavaram Works: 19/1, GST Road, Pallavaram, Chennai-600 043. India.

Tel: 91-044-2368621 Fax: 91-044-2367276 Email: plw.applications@alstom.sprintrpg.eml.vsnl.net.in.

' 1998 ALSTOM Limited

Our policy is one of continuous development. Accordingly the design of our products may change at any time. Whilst every effort is made to produce up to date literature, this brochure should

only be regarded as a guide and is intended for information purposes only. Its contents do not constitute an offer for sale or advice on the application of any product referred to in it.

ALSTOM Limited cannot be held responsible for any reliance on any decision taken on its contents without specific advice