TROUBLESHOOTING
Service Manual M4 - M10
11.07.2002
Page
57
Passive checking:
In case of malfunction, when unit is operating unproperly and is more or less
systematically indicating “Over voltage in DC bus”, check all electrical
connections in voltage measurement circuit, before advanced analyses.
For resistive voltage division network, voltage at connector (X3-13) on the
Control board shall be measured against negative bus (DC-), which is
available at the regulator A4 on the Control board.
The resistor network divides DC bus voltage in ratio below:
Rating of unit
Signal at (X3-13)
DC bus nominal
230Vac 3.58Vdc 311Vdc
400Vac 3.58Vdc 540Vdc
500Vac 3.70Vdc 675Vdc
690Vac 3.58Vdc 932Vdc
If level of signal (UCIN) follows the ratio, but still the unit is failing for “Over
voltage”, replace the Control board as instructed in section 9.3.7.
In the case that voltage is not correct at connector (X3-13), pull out the pin
(X3-13) and measure after that voltage from connector (X15-13) on Power
board. Voltage level as above in accordance with nominal voltage rating of the
unit.
If the voltage is out of tolerance (+/-1%), reason for the malfunction is failure
on the Power board and it has to be replaced as instructed in section 9.2.7.
Otherwise, excessive load by the Control board is pulling down the signal and
is indication of failure on the Control board. Replace the Control board as
instructed in section 9.3.7.
Units in power range
CX4 and CXL4, 110 - 400 kW
CX5 and CXL5, 110 - 400 kW
CX6, 90 – 315 kW
In case of larger drives, safer procedure to power up the drive is to use an
external adjustable power supply. (See 5.4.2 Basic tool requirements). To
power up the drive under investigation, disconnect wire harness from
connector X8 on Power board(s). Connect lead from (+) terminal of the
external power supply to connector X8-1 on the Power board and respectively
(-) terminal of the external power supply to negative bus of the drive. Units
equipped with dynamic braking chopper, supply (-) has to be connected
directly to the negative bus (DC-) bus bar, which is the bus bar on top in the
DC bus.