E-37Â Current Sensor Offset fault in Toshiba drive
E-37 Current Sensor Offset Error fault in Toshiba drive
Description When a VFD is powered up but not running (Stop mode), the output current to the motor should be exactly 0.0 Amps. The drive's CPU reads the Hall Effect current sensors during this idle time to determine their "Null Point" or zero-offset. If the sensors report a value significantly different from zero (e.g., 2 Amps) while the drive is stopped, the drive trips E-37. It basically means the drive's "eyes" are out of calibration and it cannot trust its own current readings, making it unsafe to start the motor. Causes
1. Magnetization: The core of the Hall Effect sensor has become permanently magnetized due to a previous severe short circuit or lightning strike.
2. Thermal Drift: The sensor electronics have degraded due to extreme heat, causing the signal to drift.
3. Auxiliary Power Loss: The +/- 15V power supply rail on the main board, which powers the sensors, is unbalanced.
4. DC Injection: External DC voltage is being back-fed into the drive output terminals from another source. Solution Disconnect the motor leads from the drive output (U, V, W). Cycle power. If E-37 persists with no load attached, the issue is internal.
Some advanced Toshiba drives allow for a manual offset calibration. Navigate to the Maintenance Menu (refer to your specific manual, usually restricted access). Look for "Current Sensor Adjustment" or "Offset Auto-Null." Run this procedure. If the offset is small, the drive can mathematically compensate for it and clear the fault.
If the offset is too large (e.g., >10% of rated amps), calibration will fail. In this case, the Current Sensors (CTs) must be replaced. On smaller drives, these are soldered to the board, requiring a full drive replacement. On large frame drives (100HP+), they are separate modules that can be unbolted and replaced individually.
Description When a VFD is powered up but not running (Stop mode), the output current to the motor should be exactly 0.0 Amps. The drive's CPU reads the Hall Effect current sensors during this idle time to determine their "Null Point" or zero-offset. If the sensors report a value significantly different from zero (e.g., 2 Amps) while the drive is stopped, the drive trips E-37. It basically means the drive's "eyes" are out of calibration and it cannot trust its own current readings, making it unsafe to start the motor. Causes
1. Magnetization: The core of the Hall Effect sensor has become permanently magnetized due to a previous severe short circuit or lightning strike.
2. Thermal Drift: The sensor electronics have degraded due to extreme heat, causing the signal to drift.
3. Auxiliary Power Loss: The +/- 15V power supply rail on the main board, which powers the sensors, is unbalanced.
4. DC Injection: External DC voltage is being back-fed into the drive output terminals from another source. Solution Disconnect the motor leads from the drive output (U, V, W). Cycle power. If E-37 persists with no load attached, the issue is internal.
Some advanced Toshiba drives allow for a manual offset calibration. Navigate to the Maintenance Menu (refer to your specific manual, usually restricted access). Look for "Current Sensor Adjustment" or "Offset Auto-Null." Run this procedure. If the offset is small, the drive can mathematically compensate for it and clear the fault.
If the offset is too large (e.g., >10% of rated amps), calibration will fail. In this case, the Current Sensors (CTs) must be replaced. On smaller drives, these are soldered to the board, requiring a full drive replacement. On large frame drives (100HP+), they are separate modules that can be unbolted and replaced individually.
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