Section 1
General Information
5-6 Troubleshooting MN715
Table 5-3 Troubleshooting
INDICATION POSSIBLE CAUSE CORRECTIVE ACTION
Command Select Incorrect operating mode
programmed. Change Operating Mode in the Level 1 Input block to one that does not
require the expansion board.
Need expansion board. Install the correct expansion board for selected operating mode.
Bus Overvoltage
Trip or
HW Overvoltage
Excessive dynamic braking power. Check dynamic brake watt and resistance parameter values.
Increase the DECEL time.
Add external dynamic braking assemblies: RGA resistor kit or
RBA transistor assembly.
DECEL Rate set too low a value Lengthen DECEL time.
Add external dynamic braking resistors or module.
Overhauling Motor load Correct problem with motor load.
Add external dynamic braking resistors or module.
Dynamic brake mis-wired. Check dynamic brake hardware wiring.
Input voltage too high. Verify proper AC line voltage.
Use step down transformer if needed.
Use line reactor to minimize spikes.
Bus Undervoltage Input voltage too low. Verify proper AC line voltage.
Use step up transformer if needed.
Check power line disturbances (sags caused by start up of
other equipment).
Monitor power line fluctuations with date and time imprint
to isolate power problem.
Disconnect dynamic brake hardware and repeat operation.
External Trip Motor ventilation insufficient. Clean motor air intake and exhaust.
Check external blower for operation.
Verify motor’s internal fan is coupled securely.
Motor draws excessive current. Check motor for overloading.
Verify proper sizing of control and motor.
Volts/Hertz ratio is wrong. Adjust the Volts/Hz parameter value.
Adjust the Base Frequency.
Adjust the Max Output Voltage.
No thermostat connected. Connect thermostat.
Verify connection of all external trip circuits used with thermostat.
Disable thermostat input at control.
Poor thermostat connections. Check thermostat connections.
External trip parameter incorrect. Verify connection of external trip circuit at J4-16.
Set external trip parameter to “OFF” if no connection made
at J4-16.
Hardware Protect Fault duration too short to be
identified. Reset control.
Check for proper grounding of power wiring and shielding of signal wiring.
Replace control board.
Heatsink Temp Motor Overloaded. Correct motor loading.
Verify proper sizing of control and motor.
Ambient temperature too high. Relocate control to cooler operating area.
Add cooling fans or air conditioner to control cabinet.
Built-in fans are ineffective or
inoperative. Verify fan operation.
Remove debris from fan and heatsink surfaces.
Replace fan or check fan wiring.