TL;DR
A converter fault on an induction power supply usually means a failed thyristor module or an overtemperature from blocked cooling. Check the fault code, then check the cooling air flow before replacing components.
What you might see
- power supply fault light on converter panel
- melt power limited below setpoint
- output frequency drifting from normal
- overtemperature alarm on the power supply cabinet
Likely causes
Thyristor module failed from overvoltage or overcurrent event
Cooling air flow to the converter cabinet blocked by a dirty filter or failed fan
Snubber capacitor failed causing uneven voltage sharing across thyristors
Gate drive circuit fault on one thyristor position
Required tools
- Multimeter for capacitor and gate circuit checks
- Replacement thyristor module (if needed)
- Filter cleaning or replacement
- LOTO kit for HV incoming power
Safety first
- High-voltage induction power supply. Only qualified personnel may work inside the converter cabinet.
- Lock out and verify zero energy on all incoming power circuits before opening the cabinet.
- Capacitors in the converter retain lethal charge after power-off. Follow the documented discharge procedure before touching components.
Procedure
- 1
Read the fault code from the power supply display and record it.
Warning: The induction power supply operates at high voltage (typically 480V to 13.8kV depending on configuration). Only qualified personnel with appropriate permits may work inside the converter cabinet. - 2
Isolate and lock out the incoming power to the converter before opening the cabinet.[1]
- 3
Check the converter cooling air filter and clean or replace if blocked.[1]
- 4
Verify the cooling fan in the converter cabinet is operating. A failed fan leads to rapid overtemperature.
- 5
If the fault code indicates a specific thyristor position, inspect that position for physical damage or discoloration.
- 6
If a thyristor module is failed, replace it with the specified replacement module. Consult the furnace manufacturer service documentation for the module specification.
- 7
After repair, restore power with reduced setpoint first and monitor the converter temperature for 10 minutes before returning to full power.
Sources
Inductotherm (Inductotherm Group) Inductotherm VIP-I / Power-Trak Induction Melting Furnace general technical documentation, Inductotherm (Inductotherm Group)
Inductotherm power supply service documentation, converter fault diagnosis and module replacement procedures (general)
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