Publication 2364F-5.05 - March 1999
4-12
Testing Components
Testing the Control Power Filter
The control power filter reduces the noise in the control power. The
effectiveness of the filter can be checked by viewing the waveforms before
and after the filter (there should be less noise seen after the filter, as shown
in Figure 4.7).
Push the disconnect lever to off and wait for all voltage to discharge from
the unit. Do not continue until all voltage has dissipated from the DC bus.
Verify that there is no voltage across the DC bus (see Figure 4.12 and
Figure 4.13 for check points).
Verify that there is no voltage across the subcomponents of the control
power filter.
Set meter for resistance and check the resistor. For 4 kHz filters, the
resistance should be 0.8-1.4 ohms (1 ohm rating). For 2 kHz filters, the
resistance should be 1.3-1.9 ohms (1.5 ohm rating).
Check the continuity between C1-1 and the connection point for the control
power transformer (PT1).
If the filter has failed any of these tests, it may be damaged. Replace the
filter and consider replacing any associated wiring or fuses, as necessary.
Figure 4.7
Voltage Waveforms Ahead and After the Control Power Filter
Typical Control Power–Ahead of Filter
Typical Control Power–After Filter
