Danfoss VLT HVAC Drive FC 100 Service Manual page 123

6 Test Procedures
When using an oscilloscope, the readings should appear as in Figure 6-18.
Figure 6.18: Gate Signal Waveform from Gate Drive Card. IGBT Gate Signal measured on the Gate Drive
6
Card: 5 volts per division vertical scale, 50 microseconds per division time scale. Unit running at 30 Hz.
An incorrect reading of a gate signal indicates the gate drive card is defective or the signal has
been lost prior to it arriving at the gate card. The gate signals can then be checked with the signal
test board to verify their presence from the control card to the power card as follows.
12.
13.
14.
The waveform should appear as in Figure 6-19.
Figure 6.19: Gate Signal Waveform from Signal Test Board. IGBT Gate Signal measured with the Signal Test
Board: 2 volts per division vertical scale, 50 microseconds per division time scale. Unit running at 30 Hertz.
15.
An incorrect reading of a gate signal indicates either the power card is defective or the signal has
been lost prior to arriving at the power card. There is no test to verify the signals directly out of
the control card. The power card would be suspect if a single gate signal is incorrect. The control
6-32
Insert the signal test board into power card connector MK104.
With scope probe ground connected to terminal 4 (common) of signal board, measure
six gate signals at signal board terminals 25 through 30.
Place the adjustable frequency drive in run at 30 Hz.
Using a DVM, again check these same signal board terminals. DVM should read 2.2 to
2.5 VDC.
MG.90.L1.22 - VLT
High Power Service Manual for VLT
® is a registered Danfoss trademark
®
FC Series
Adjustable Frequency Drives