YASKAWA P7 User Manual page 167

Check
24Vdc Cooling Fans
(Heat Sink & Internal)
230/240Vac Cooling Fans
(Heat Sink)
Cooling Fan Fuse
Table 6.6 Main Circuit Test Procedure
The Heat Sink & Internal Cooling Fans cool the heat sink as well as the output transistor mod-
ules of the Drive.
1. Conduct a visual inspection to ensure the fan turns freely.
2. If there is no physical evidence that the fan is bad, the fan motor can be checked with a
digital mutli-meter.
3. Set the digital multi-meter to the R x 1 scale.
4. Measure across the fan motor terminals. If zero ohms are measured, conclude that the fan
motor is shorted. If infinite ohms are measured, conclude that the fan motor is burned open.
5. If the fan is not working, then disconnect the fan and apply 24Vdc to the fan to test the
motor.
The Heat Sink Cooling Fans cool the heat sink to remove heat from the Drive.
1. Conduct a visual inspection to ensure the fan turns freely.
2. If there is no physical evidence that the fan is bad, the motor can be checked with a
digital mutli-meter.
3. Set a digital multi-meter to the R x 1 scale.
4. Measure across the fan motor terminals. If the fan motor is good, the measured value
should be about 500 ohms. If zero ohms are measured, conclude that the fan motor is
shorted. If infinite ohms are measured, conclude that the fan motor is burned open.
If the fan is not working, then disconnect the fan and apply 230/240Vac to the fan to test the
motor.
Large Drive units contain a Cooling Fan Fuse. It is located on either the Gate Drive Board
(3PCB) or the Tap Change Board (8PCB). If the Cooling Fan Fuse is open, then the
230/240Vac cooling fans may be defective.
1. Set a digital multi-meter to the R x 1 scale.
2. Place one lead of the multi-meter on one side of the fuse and place the other lead of the
multi-meter on the other side of the fuse.
3. If the fuse is good, the measured value will be zero ohms.
If the fuse is bad, the measured value will be infinite ohms.
Diagnostic & Troubleshooting 6 - 23
Procedure