E-29Â Control Power Undervoltage fault in Toshiba drive
E-29 Control Power Undervoltage fault in Toshiba drive
Description While "UP" (Undervoltage Protection) refers to the high-voltage Main DC Bus, E-29 refers to the low-voltage control power supply (usually 24VDC or 5VDC internal rails). This supply powers the CPU, the display, and the I/O terminals. If this voltage sags, the CPU cannot calculate reliable data and trips E-29 to avoid erratic behavior. Causes
1. Overloaded 24V Output: The user has connected too many sensors, relays, or pilot lights to the drive's "P24" or "PP" terminal, drawing more current than the internal regulator can supply (usually limited to 100mA or 200mA).
2. Short Circuit in Control Wiring: A field wire connected to a digital input has pinched and shorted to ground, dragging down the 24V rail.
3. Internal Power Supply Failure: The DC-DC converter capacitors on the control board are failing (aging). Solution Disconnect ALL control wiring from the terminal strip (logic inputs, analog I/O, relay outputs). Leave only the keypad connected.
Cycle power. If E-29 disappears, the problem is in your field wiring. Reconnect wires one by one until the fault returns to find the short. Check your external load calculation—if you are driving heavy contactor coils directly from the VFD logic outputs, you likely need an interposing relay.
If E-29 persists with all external wires disconnected, the internal power supply is dead. The drive or control board needs replacement.
Description While "UP" (Undervoltage Protection) refers to the high-voltage Main DC Bus, E-29 refers to the low-voltage control power supply (usually 24VDC or 5VDC internal rails). This supply powers the CPU, the display, and the I/O terminals. If this voltage sags, the CPU cannot calculate reliable data and trips E-29 to avoid erratic behavior. Causes
1. Overloaded 24V Output: The user has connected too many sensors, relays, or pilot lights to the drive's "P24" or "PP" terminal, drawing more current than the internal regulator can supply (usually limited to 100mA or 200mA).
2. Short Circuit in Control Wiring: A field wire connected to a digital input has pinched and shorted to ground, dragging down the 24V rail.
3. Internal Power Supply Failure: The DC-DC converter capacitors on the control board are failing (aging). Solution Disconnect ALL control wiring from the terminal strip (logic inputs, analog I/O, relay outputs). Leave only the keypad connected.
Cycle power. If E-29 disappears, the problem is in your field wiring. Reconnect wires one by one until the fault returns to find the short. Check your external load calculation—if you are driving heavy contactor coils directly from the VFD logic outputs, you likely need an interposing relay.
If E-29 persists with all external wires disconnected, the internal power supply is dead. The drive or control board needs replacement.
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