Testing and Maintenance of Protective Gear

Testing and Maintenance of Protective Gear:

Classification of Relay Testing : Classification of Relay Testing are usually conducted to demonstrate that: the relay will operate correctly to clear a fault; and the relay will remain inoperative on faults outside its specified zone. To ensure correct operation of relay, it is advisable to set up a relay testing programme to suit the system needs. The system conditions should be simulated before testing a particular relay. Broadly speaking the Classification of Relay …


Current Transformer Tests : Current Transformer Tests are generally mounted in the switchgear when it is delivered to site and may not be easily accessible. The normal tests which are carried out can easily be performed with the CTs mounted in the switchgear. These tests are: Polarity Check, Ratio Check and Magnetization Curve. Polarity Check: This check is necessary to see the relative polarity of the primary and secondary terminals when terminals are …


General Methods of Testing Protective Gear : The General Methods of Testing Protective Gear are namely, Primary Injection, Secondary Injection, Measurement of Time, Primary Injection: These tests are limited by the manner in which current can be passed through the primary winding of the current transformers of the protective gear under test. Generally it is possible to obtain access to the primary connections to enable current at low voltage to be injected, but in certain …


Heavy Current Test Plant : Heavy Current Test Plant – Simulating the exact fault conditions as would occur in practice is a difficult and a tedious job. The plant for providing the current for these tests as pointed out earlier ought to be of considerable capacity and special design. To ensure that the behavior of the protection under transient conditions is fully proved, it is often necessary to assemble the complete …


Potential Transformer Tests : The three Potential Transformer Tests are namely, Polarity check, Ratio check and Phasing check. Polarity check: Polarity check in Potential Transformer Tests is performed in the same way as that for a CT. If the PT is of the capacitor type then the polarity of the transformer at the bottom of the capacitor stack should be checked. Ratio check: A simple test for ratio can be made by connecting voltmeters to …


Testing Overcurrent Relay : Test benches are used for proving the design characteristics of relays. These are provided with accurate timing apparatus and calibrated current and voltage supplies. The basic circuit for Testing Overcurrent Relay is shown in Fig. (8.1). The harmonic content in the current wave form is kept to within 2% of the fundamental by adjusting the current through a choke which has an impedance at least six times …


Updated: May 1, 2020 — 11:22 pm