Abb CA16 relay 1

[Pit2005]

I have been attempting to build a test for a ABB/Westinghouse ca16 bus differential relay. The software and test set I am using is protest paired with a doble 6150. I can't seem to get the percent differential test to work with the instructions in the manual. If anyone could point me in the correct direction as far as what test connections to use or possibly send me a test plan they already have any help would be greatly appreciated.

 

[DTR2011]

The CA-16 is a very high burden relay to test. If you note in instruction manual, that the test schematic used for testing with a variable resistor utilizes a 240 VAC source, vs. many EM relays would utilize 120 VAC source for similar test set up.

In general, you want to test 2 current inputs at a time, ie 2 different sources. There are some CA-16 relays that take up to 4 sets of CT's and it is unlikely you would have enough power in test set to complete without overloading. I suggest you utilize that range in the test set that provides the highest compliance voltage, as otherwise your doble will not be happy and beep a lot with source errors.

In general, you would want to use a current ramping macro to find minimum pick up - do this for each CT input. For checking the slope characteristic, you need to apply 2 currents. There are different methods of achieving this. One is to hold one current static, while ramping from the trip region (above the slope line) down into the restrain area. The other is to hold bot current magnitudes static, while varying the phase angle of one current to create the diff current. The key is that you will expect your trigger to go from an "on" state to an "off" state, testing down into the restrain area of the relay characteristic.

Keep an eye on the duration and magnitudes of the currents as you want to keep the smoke in the relay. Depending on where you are in the slope characteristic, you may want some kind of pulsed ramp, where you limit the duration of the applied current to a reasonable time limit and allow a cool down period between test shots. A 3:1 ratio of cool down to test duration is generally a safe way to go, but check the manual. Since diff is high speed, you are looking at ~10 cycles for test duration, which should be more than sufficient.

After minimum pick up and slope has been checked for all restraint windings, you can do a state sequence test to check the operate time. Don't forget to check the target / seal in unit for proper operation. I recently found an ABB/West HU relay that would trip the lock out relay, but did not target for the trip.