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CURRENT TRANSFORMERS TEST SET

C.T. testing set is meant for determination of PHASE ANGLE ERROR AND RATIO ERROR OF Current transformer having secondary rated for 5 Amps. or 1 Amp. which are intended to be used on 50 Hz. The measurement is on principle of comparison and null indication on magnetic balance bridge. 

The basic unit is sensitive magnetic comparator and also it incorporates electronic null detector to facilitate the balance. The reference Current 5A. or IA. obtained from Standard Current Transformer and in comparison to that the vector length and phase displacement is measured. The ratio error in percentage and phase displacement in minutes are directly compared and indicated on dials.

The two current vectors, one from Standard Current Transformer and the other from the Current Transformer under test energises the high permeability magnetic core and then the associates windings try to annual the residual magnetism which occurs due to error. The differential vectors will be proportional to phase error and ratio error magnitudes. The Standard Current Transformer injects proportional currents in phase and also of controllable value. The control is done by ratio error dial. The injection current tries to annual in phase component vectors.

The high resolution quadrature circuit fed from the same standard current transformer also injects proportional and controllable current in quadrature. Due to this injection the quadrature of differential vector is annualed. The phase angle dial controls this magnitude.

The amount of injection will be proportional to phase error and ratio error and thus two quantities can be measured directly if perfect balance is achieved. The electronic tuned amplifier detector circuit measures the flux value picking up the current from the balancing magnetic circuit. At perfect balance condition fundamental frequency flux in the comparator is negligible and the null is achieved.

The C.T. Testing Set provides the following ranges:-

PHASE ANGLE ERROR                                             RATIO ERROR:
0 to 20 min. with x 1 range.                                   0 to 0.5 % with x 1 range. 
0 to 100 min. with x 5 range.                                  0 to 2.5 % with x 5 range.
0 to 200 min. with x 20 range.                                0 to 10.0% with x 20 range.

The set provides the following components:-
1. Separate terminals to connect Standard C.T. and Test C.T. secondaries.
2. Ratio error and Phase angle error calibrated dials.
3. Range selecting switch.
4. Polarity check indicator.
5. Ammeter to measure current injected in percentage.
6. Null detector with sensitivity control.
7. Terminals to connect burden box.
8. Aux. power supply to energies electronic null detector.
9. High permeability magnetic core.
10. Secondary current selector 1A.or 5A.

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THE CT TEST SET REQUIRES THE FOLLOWING ACCESSORIES

1. STANDARD CURRENT TRANSFORMER

PRIMARY RANGES           : 100-75-50-25-10 & 5 Amps.
SECONDARY                  : 5 Amps. and 1 Amp. selectable
BURDEN                        : 10 VA.
CLASS OF
ACCURACY                    : 0.2

2. PRIMARY INJECTION KIT

Primary Injection Kit is designed to operate on single phase 230/240 Volts AC 50 Hz. to develop smooth & continuous test current. The test set gives high current output at low cost and with inherent safety at minimum precaution. 

TECHNICAL SPECIFICATION :

INPUT                   : 230/240 V single phase AC 50 Hz.
OUTPUT CURRENT   : As per your requirements
CURRENT RANGES    : As per your requirements
BURDEN (Capacity)  : As per your requirements
DUTY CYCLES         : 10 min ON & 10 min OFF
COOLING                : Natural Air Cooling
INSTRUMENTS         : 1 No. AC voltmeter to measure input voltage
                              1 No. AC Ammeter C.T. operated having basic range of 
                                      5A/1A associated with multiratio current transformer 
                                      with suitable ranges.
                              1 No. Time Interval meter, Digital range 
                              0-999 milliseconds (optional)
CONTROL                : One knob control to vary output current.

Aux. Contacts for Timer connection. Terminals for connecting relay under test. High current output on suitable terminals.

Current Ranges     Capacity            Current Ranges     Capacity                Current Ranges      Capacity
0-150-300 A          3 kVA               0-500-1000 A        5 kVA                    1000-2000 A         10 kVA
0-250-500 A          3 kVA               0-1000-2000 A      5 kVA                    1500-3000 A         10 kVA
0-400-800 A          5kVA                1500-3000 A         6 kVA                    2500-5000 A          6 kVA

3. C.T. BURDEN BOX

(a) Burden box 0.8 Lag. Power Factor. 
     Range 40 VA IN STEP of 2.5 VA.
(b) Burden box unity Power Factor.
     Range selectable 1.25-2.5-3.75 & 5 VA.

4. POLARITY TEST SET

For checking the polarity of current Transformers under test. It consists of a built-in battery with known polarity galvanometer indicating correct or wrong polarity.

* C.T. Magnetization Test Set can be supplied on request 

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