Testing Of Protective Devices

That would be the method recommended by the manufacturer of the various equipment.

Do some research on the web.

Why would you want to test them at all? If you have bought the system from a reputed manufacturer, you can rest assured that they would have tested these as per standards.

There is no way you can test them as well as the manufacturer can.

1. MCCB - You need a current-feedback-stabilised low voltage/high current source to pass currents from rated to 10Xrated current. Do you have such a source?

2. Thermal overload relay - ditto as above

3. Thermistor relay - may be you can do secondary injection as a low voltage input...you will need to check with the manufacturer.

4. Level relay - should be quite easy to see whether it switches the motor on and off as the level rises.

5. No idea

6. See whether the heater heats up? or is it open-circuited in transit ?

To repeat, not worth testing. Just go with a reputed supplier and trust them.

Thank you for your response. I think my question was a bit ambiguous. There is as you say, no need to test components from reputable manufacturer's. What I meant was to test the settings of such devices. For example, we can check the settings of a thermal overload relay by changing the range and confirm that the motor trips. Similarly, pressure and level relays can also be checked by changing the pressures and levels (I am refering to water pumping schhemes).

Good idea.

Ah, i see now. Stupid of me, i am sorry.

i suggest you ignore the MCCB. Its thermal protection is much cruder than that of the thermal relay. Its magnetic trip will respond to short-circuits (not even locked rotor), and is there for overall protection. In fact, properly selected fuses would be better, unless you have some code requirement to use an MCCB.

Now for the relay. You can set it at the nameplate FLA of the motor, and do the test using a stabilised current source as i said before. As per IEC, it is not supposed to trip at 5% overcurrent and must trip at 20% overcurrent. You can fine-tune this setting depending on whether the relay trips or not.

Why stabilised source? Since this will be a low-voltage high current source, it will be of low VA. As the relay elements heat up, their resistance will increase somewhat, and at a fixed voltage, the current will drop. So, you need to increase the voltage to compensate. The Doble equipment quoted by Sriram can do this. There are also other makes. Depends on where you are.

If you are interested in testing the protection relay.Then you must have this KIT.

It is better to buy from a reputed manufacture as said by Kvsridhar.we used them only for testing protection relays in substation not for motor control circuits.

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Reply me if i am WRONG .