Drive cooling fan
Common heat-related VFD and servo-drive failure point.
Yaskawa VFD Fault ER — What It Means
The ER fault on a Yaskawa drive (G7, F7, E7, A1000, V1000 series) indicates an EEPROM error. The drive’s non-volatile memory (EEPROM) stores all parameter settings and configuration data. When the drive detects a checksum mismatch, read/write failure, or data corruption in the EEPROM, it throws an ER fault and typically defaults to factory parameters or halts operation. The drive cannot run reliably without valid stored parameters.
Common Causes
- Power interruption during parameter write — If input power was lost or interrupted while the drive was saving a parameter change to EEPROM, the stored data can become corrupted.
- EEPROM end of life — EEPROMs have a rated write cycle limit (typically 100,000 cycles). Drives with frequent parameter changes over many years can exceed this limit.
- Electrical noise or surge — Electrical transients on the power supply or control wiring can corrupt EEPROM data, particularly in environments with frequent switching loads.
- Failed control board — The EEPROM chip itself or the interface circuit on the control board has failed. This is a hardware fault requiring board replacement.
Step-by-Step Fix
- Record current parameters before any action — If the drive is still accessible (fault does not prevent display), use the keypad to navigate all parameter groups and record current values, or use Yaskawa’s DriveWizard software to upload parameters.
- Perform an EEPROM initialize — Access the drive’s diagnostic or maintenance menu. On Yaskawa drives, this is typically under A1-03 (Initialize Parameters). Set A1-03 to 2220 or 3330 to perform a factory reset and re-initialize the EEPROM. Note: this will clear all parameters to factory default.
- Re-enter or download parameters — After initialization, manually re-enter all application parameters, or use DriveWizard to download a previously saved parameter file if one is available.
- Test drive operation — Run the drive through its normal operating range and confirm the ER fault does not return after a power cycle.
- Check input power quality — Install a power line monitor or ask the utility about power quality issues at the site. Install a line reactor or surge suppressor upstream of the drive if electrical noise is suspected.
- Replace the control board if ER persists — If the EEPROM initialize fails to clear the ER fault or the fault returns immediately, the EEPROM chip or control board is hardware-failed and requires replacement.
- Reset and confirm — After board replacement or successful EEPROM recovery, perform a full operational test and save a parameter backup to DriveWizard.
Parts Often Needed
| Part | Notes |
|---|---|
| Yaskawa control board (PCB) | Order by drive model and frame size; match control software version |
| Line reactor (3%) | Add upstream of drive to reduce voltage spikes from power line |
| Surge suppressor | Install on control wiring if noise is suspected cause |
Technician Tips
When diagnosing VFD faults, always check the drive’s fault history before resetting. Modern drives store the last 5-10 faults with the drive state at the time (running, accelerating, decelerating, stopped). An overcurrent fault that occurs only during acceleration points to incorrect motor data or mechanical binding. The same fault during deceleration suggests regeneration issues. A ground fault that clears after disconnecting the motor and returns when reconnected means the motor or cable insulation has failed.
Prevention: Schedule annual infrared scanning of drive cabinets. Loose power connections and failing capacitors produce heat long before they cause faults. A 5-minute scan can prevent hours of unplanned downtime.
Need Replacement Parts?
Before ordering, match the drive part to the model number, electrical rating, and failure symptom. Check current prices on Amazon - prices and availability change frequently.
When to Call a Pro
EEPROM failures that do not respond to initialization indicate a hardware fault. A Yaskawa-authorized technician can replace the control board and verify correct firmware and parameter configuration for your application.