EPH (Output) Output Phase Loss fault in Toshiba drive
EPH (Output) Output Phase Loss fault in Toshiba drive
Description While Input Phase Loss monitors the incoming power, Output Phase Loss monitors the connection to the motor. The drive detects that current is flowing in only two of the three output phases (U, V, W). Running a 3-phase motor on 2 phases (single-phasing) causes extreme vibration, noise, and rapid overheating of the motor windings. Causes
1. Maintenance Switch: A local isolator switch near the motor has a bad contact or was opened while running.
2. Loose Termination: A wire has vibrated loose at the motor peckerhead or the drive output.
3. Motor Failure: Internal open circuit in the motor windings (burnt winding).
4. Oversized Drive: Testing a very small motor on a large drive. The current drawn is so low that the drive thinks a phase is disconnected. Solution Warning: High Voltage. Lock out power.
Check continuity. Disconnect the motor cables from the drive (U, V, W). Use a multimeter to measure resistance phase-to-phase looking towards the motor (U-V, V-W, W-U). All three readings should be low (e.g., 2.5 ohms) and balanced. If one reading is "OL" (Open Loop) or infinite, you have a broken wire or blown motor winding. Walk the cable run and check every junction box and disconnect switch.
If the motor and cables test fine, reconnect them. If you are testing a small motor (e.g., 1HP) on a large drive (e.g., 100HP), the drive's current sensors cannot detect the load. You must disable the "Output Phase Loss" parameter (F605) for bench testing. Remember to re-enable it for the actual application.
Description While Input Phase Loss monitors the incoming power, Output Phase Loss monitors the connection to the motor. The drive detects that current is flowing in only two of the three output phases (U, V, W). Running a 3-phase motor on 2 phases (single-phasing) causes extreme vibration, noise, and rapid overheating of the motor windings. Causes
1. Maintenance Switch: A local isolator switch near the motor has a bad contact or was opened while running.
2. Loose Termination: A wire has vibrated loose at the motor peckerhead or the drive output.
3. Motor Failure: Internal open circuit in the motor windings (burnt winding).
4. Oversized Drive: Testing a very small motor on a large drive. The current drawn is so low that the drive thinks a phase is disconnected. Solution Warning: High Voltage. Lock out power.
Check continuity. Disconnect the motor cables from the drive (U, V, W). Use a multimeter to measure resistance phase-to-phase looking towards the motor (U-V, V-W, W-U). All three readings should be low (e.g., 2.5 ohms) and balanced. If one reading is "OL" (Open Loop) or infinite, you have a broken wire or blown motor winding. Walk the cable run and check every junction box and disconnect switch.
If the motor and cables test fine, reconnect them. If you are testing a small motor (e.g., 1HP) on a large drive (e.g., 100HP), the drive's current sensors cannot detect the load. You must disable the "Output Phase Loss" parameter (F605) for bench testing. Remember to re-enable it for the actual application.
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