330-0015

Check power supply unit status

Inspect the main power supply unit LED indicators. Green LED should be steady, indicating proper DC bus voltage generation. Check for fault LEDs or error codes on the PSU module.

Work must be performed by qualified electrical personnel. Lethal voltages present even when machine is powered off due to DC bus capacitors.

Measure DC bus voltage

Using appropriate high-voltage test equipment, measure DC bus voltage at the inverter input terminals. Standard specification is 560-600VDC for 400VAC input systems. Voltage below 500VDC will typically prevent inverter ready status.

High voltage measurement requires proper PPE and qualified personnel. Ensure proper isolation and test equipment rated for DC bus voltages.

Check DC bus fuses and contactors

Verify that all DC bus fuses are intact and DC bus contactors are closing properly. Check for signs of arcing or thermal damage at connection points. Measure voltage on both sides of contactors when closed.

On multi-axis systems, compare DC bus voltage across all inverter modules. If only one axis shows low/no voltage, suspect local connection or distribution issue rather than main PSU failure.

Inspect inverter power connections

Check all DC bus bar connections, screw terminals, and press-fit contacts at the inverter module. Loose connections can cause voltage drops or intermittent RDY failures. Torque all connections to specification.

Thermal cycling can loosen power connections over time. Check for discoloration around terminals indicating overheating from loose connections.

Check inverter module LEDs

Examine the LED indicators on the drive inverter module. Red LED typically indicates fault condition. Refer to the specific drive module documentation for LED fault code interpretation. Note any blinking patterns.

On UM12x series drives, a slow blinking red LED indicates thermal fault, while fast blinking indicates hardware fault. Different drive generations have different LED patterns.

Access drive diagnostics via MOD function

Press MOD key, select SERVICE menu, navigate to Drive Diagnostics. Select the affected axis drive and review status registers, fault history, and temperature readings. Document any logged fault codes.

Use MOD → Service → Drive Info → Detail View to see real-time inverter status bits. Bit patterns will show which specific protection circuit has triggered.

Check cooling system operation

Verify cooling fans are operational and airflow paths are unobstructed. Check for dust buildup on heatsinks. Measure actual drive temperature if thermistor connections are accessible. Allow 30-minute cooldown if thermal fault suspected.

Even with power removed, heatsinks may remain hot enough to cause burns for 30+ minutes after shutdown.

Perform inverter isolation test

Disconnect motor cable from inverter output and attempt to clear fault. If inverter achieves RDY with motor disconnected, suspect motor or cable fault. If RDY still fails, inverter module is defective.

Motor cable disconnection must be performed with power removed and after DC bus discharge. Never disconnect motor under load.

Inspect controller card connections

Power down system and check all ribbon cables, multi-pin connectors, and backplane connections between the CC (Controller Card) module and inverter power section. Reseat X4x connector series on controller card and corresponding inverter connectors.

On modular drive systems, the control signals typically route through backplane connectors. Clean contacts with isopropyl alcohol and check for bent pins before reseating.

Check controller card LED status

Examine LEDs on the CC controller card for the affected axis. RUN LED should be green and steady. COM or ERR LEDs indicate communication issues. Consult the specific controller card documentation for LED interpretation.

The CC module typically has axis-specific LEDs. Compare LED patterns between working axes and the faulted axis to identify communication anomalies.

Verify enable signal path

Using MOD → Service → PLC Diagnostics, monitor the enable signal for the affected axis. Verify that the control is commanding enable when attempting axis activation. Check PLC program logic for enable interlock conditions.

Search for MP1018 (axis enable release) in machine parameters. This parameter controls enable signal routing and may be misconfigured after control updates.