Type CDAG Combined Overcurrent and Earth Fault Relay
Type CDAG Combined Overcurrent and Earth Fault Relay Features l
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Identical time/current characteristics on all taps for overcurrent units. Instantaneous sensitive earth fault protection. High stability on external earth faults for restricted earth fault protection.
Types CDAG 31, 33 and 34 are type CDAG relays having inverse, very inverse and extremely inverse time overcurrent units respectively and an instantaneous earth fault unit, type CAG 14. Types CDAG 51, 53 and 54 are types CDAG 31, 33 and 34 relays having highset instantaneous units on the two overcurrent elements.
Comprehensive range of auxiliary and highset unit ratings for phase faults.
Technical data
Dust tight drawout case and tropicalised finish.
1A or 5A
Application Phase and earth fault protection of transformers, ac machines, feeders etc. The relay provides inverse time phase fault protection and instantaneous restricted earth fault protection.
A highset instantaneous overcurrent unit can be fitted on the two overcurrent elements to provide instantaneous protection under maximum short circuit conditions and to improve discrimination on time graded protective systems. For a general description of the highset instantaneous unit, refer to the CAG 17 publication.
Operating time l
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Earth fault units 0.025 sec. at 5 times the current setting.
Settings Phase fault units
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Phase fault units 0 - 3.0 sec., 0 - 1.3 sec., 0 - 1.5 sec., 0 - 0.6 sec; at 10 times the current setting, depending on the characteristic selected.
Current ratings
For time/current characteristics, resetting times and overshoot of phase fault units, refer to CDG 11, 13 and 14 publications.
IDMT element: 50 - 200% - adjustable in seven steps. Highset unit:
Burden
250% - 2000%
Description Type CDAG is a triple pole relay and comprises two induction disc units (type CDG 11, 13 or 14) for phase fault protection and an instantaneous attracted armature unit (type CAG 14) for restricted earth fault protection. Types CDG 11, 13, 14 and type CAG 14 relays are described in the relevant publications.
Continuously variable external stabilising resistors of 200 ohms and 50 ohms are supplied as standard for 1A and 5A relays respectively. Stabilising resistors with other ohmic values are also available.
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Earth fault units
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20 - 80% or 10 - 40% adjustable in seven equal steps.
Phase fault units Typical impedance/current curves for the various types of phase fault units are given in the CDG 11, 13 and 14 publications.
Overcurrent element
CDG 11 standard
CDG 11 low burden
VA burden at current setting on lowest tap
2.0
0.75
1.0
0.5
VA burden at current setting on highest tap
3.5
1.3
3.0
2.5
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Earth fault units 0.9VA at current setting on lowest tap. 1.0VA at current setting on highest tap.
CDG 13
CDG 14
Thermal ratings l
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Phase fault units
22A for 0.5 s - 0.2A tap
Continuous:
92A for 0.5 s - 2.0A tap
(for 60°C rise in coil temperature) Operating coil tap Multiples of current setting
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1
2
3
4
5
6
7
4.5
3.7
3.2
2.7
2.6
2.4
2.2
Two pairs, self reset make contacts and a hand reset operation indicator provided.
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Continuous:
Make and carry for 0.5 s, 2500VA with maxima of 10A and 660V ac or dc.
(for 60°C rise in coil temperature)
Auxiliary unit contact
Earth fault unit
Operating coil tap Multiples of current setting
1
2
3
4
5
6
7
8.5
7.7
6.9
6.4
5.7
5.3
5.0
Short time: 20 x setting current for 3 sec. on any setting.
Auxiliary units and operation indicators l
Accuracy Phase fault units Error class index E 7.5 as per BS 142 7.5 as per IS 3231 Frequency error Timing error less than 8% for a frequency variation of 2 Hz. Temperature error Under reference conditions of +45°C to 5°C.
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CDG 11 1.3 sec relay: 4% and +4% CDG 13: 1% and +1% CDG 14: 3% and +5% Earth fault units Error class index E 5.0 as per BS142, 5.0 as per IS 3231.
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Make and carry for 0.5 s, 7500VA with maxima of 30A and 660V ac or dc. l
Earth fault unit Make and carry for 0.5 s, 7500VA with maxima of 30A and 660V ac or dc.
Phase fault units
Insultation
Auxiliary unit with two pairs of self reset contacts to reinforce the disc contact and a hand reset operation indicator provided. Auxiliary unit may be series connected (current operated) or shunt connected (voltage operated). Series auxiliary unit is used in series with breaker trip coil or tripping relay and has two current taps selected by screw connection.
The relay meets the requirements of IS3231/IEC 255-5 series C - 2 KV for one minute.
Voltage operated auxilary unit Type CDAG 51, 3VA version is self powered. For other models, voltage operated auxiliary unit: 30, 110 or 220V dc refer relevant publication for burden details.
CDG 11 3.0 sec relay : 3% and +4%
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Phase fault unit Disc contact
20 x setting current for 3 sec. on any tap.
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Earth fault unit
Contact ratings
Short time:
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Current rating
Current operated auxilary unit 0.2/2 amp. (two taps) minimum operating current.
Case 3D vertical case or horizontal suitable for flush and finished eggshell black and tropicalised. Suitable trip isolating switch and CT shorting switches are provided on the cradle assembly/case.
A B C
T1
T2
T1
T2
Stabilising resistor Alarm Trip
Information required with order T1
T2 CT shorting contacts
1. Type of relay CDAG 31, 33 or 34, CDAG 51, 53 or 54.
+
1
2
3
4
5o/c 6
7E/F 8
9 o/c 10
2. Current transformer secondary rating.
12
ISOL SW.
3. Current setting range (earth fault units). Note: One overcurrent element is shown. The other overcurrent element will be similarly connected. Alarm and trip contacts are paralleled.
Figure 1: Typical external and internal connections for type CDAG relay with shunt reinforcing units on phase fault element and type CAG 14 earth fault unit.
Dimensions and weights Maximum overall dimensions Relay
Case size
Approximate
Height mm
Width mm
Depth* mm
gross weight Kg.
CDAG 31, 33 or 34
3D Hor.
233
454
203
15.5
CDAG 51, 53 or 54
3D Vert.
524
170
203
20
Stabilising resistor
41 mm diameter x 273 mm long
* 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 and are suitable for use in normal tropical environments.
4. Characteristic (0 - 3.0 sec. or 0 - 1.3 sec. at 10 times current setting, when CDG 11 phase fault elements are required). 5. Burden (3VA or 1VA when CDG 11 phase fault elements are required). 6. Auxiliary voltage (for shunt auxiliary units of phase fault elements). 7. Trip circuit current (for series sealing units of phase fault elements). 8. Case. 9. For CAG 14 earth fault unit (a) Application (restricted earth fault/sensitive earth fault) (b) Current transformer and secondary winding resistance (c) Lead resistance from CTs to the relay. (d) Maximum and minimum fault levels.
AL ST OM Li mi te d Pallavaram Works: 19/1, GST Road, Pallavaram, Chennai-600 043. India. Tel: 91-044-2368621 Fax: 91-044-2367276 Email:
[email protected]. © 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.
