The Megger OCR models are used for testing the timing of oil circuit reclosers. If the OCR has a computer port then it should be capable of interfacing with PowerDB Lite software.
During timing tests, PowerDB will send the instrument some of the test settings, such as number of shots, current measuring range, etc. PowerDB will initiate the test set output and the timing test, and it will also capture the timing results into the test form.
There will be times when it appears that PowerDB “times out” and will not capture the test results from the instrument. This may happen even though the OCR unit seems to properly run its course and the recloser locks out after the correct number of operations.
The reason for this is that after a lockout, the OCR waits for 5 seconds to verify that the recloser has truly locked out and that current flow does not restart. If the entire test has taken 15 seconds, then the OCR waits 5 more seconds before sending results to PowerDB. This total time can sometimes be 20-30 seconds or more depending on the recloser ratings and the applied test current. It may be even longer if the recloser is being closed manually during the test.
The PowerDB test form has a field for Maximum Total Time, which defaults to 20 seconds. If 20 seconds passes before the readings are sent, PowerDB itself will time out and not record the readings. The 20 seconds setting in PowerDB does not affect the OCR. It only provides a maximum time that PowerDB will wait for readings.
If PowerDB does not capture readings after the conclusion of a seemingly normal test sequence by the OCR, the Maximum Total Time setting in the test form should be increased. A good starting point would be increasing the setting from 20, to 25 or 30 seconds. The only downside to this is that PowerDB may wait the entire time of the setting to display the results. So, increasing the value to some much higher value, such as 60 seconds, isn’t recommended as it may just be making your testing take longer than it should.
Standard OCR models are generally pre-programmed for a 20 second maximum test time, except for units with the computer interface, which includes a thumbwheel setting. The thumbwheel can be set up to 199 seconds. Keep in mind that this is not in any way affected by the setting in the PowerDB test form.