UniMac Washer-Extractor Error Code Ed02: High DC Bus Voltage
Ed02 means the DC bus voltage inside the motor drive climbed too high, so the drive protected itself and the batch stopped. Power the machine down and have a qualified person check the voltage at the disconnect.
High: the drive trips and the batch stops, so the washer cannot be relied on until the supply or load cause is found.
- Code
- Ed02
- Maker
- UniMac
- Equipment
- Industrial laundry
- Applies to
- CHM495R family washer-extractor front-end control (20-100 lb)
What does UniMac error code Ed02 mean?
The motor drive on a UniMac UC-series washer-extractor converts incoming AC line power into a DC bus, and from that bus it builds the variable-frequency power that spins the motor. The drive watches the bus voltage all the time. If the voltage rises above the upper limit, the capacitors and power electronics are at risk, so the drive trips to protect itself, the batch stops and Ed02 appears. A high bus can come from two directions. Either the incoming line voltage is higher than the washer is built for, or a spike on the supply feeds the bus, or the motor pushes energy back into the drive when it brakes a heavy, fast-spinning load. A drive board that misreads the bus voltage is the fourth possibility. The manual lists those four. The message applies to Design 2 and 3 models only. Because the supply voltage must be measured at the disconnect, this is not a job for laundry staff, but a lighter test batch can help show whether the load is involved.
Affected models and control systems
This applies to the CHM495R family of UniMac UC-series washer-extractors, 20 to 100 lb, with the motor drive, such as the UCH020GNF. It is limited to Design 2 and 3 machines.
Code numbers and their meaning can change between control generations. We match the full model and control before acting on a code.
What you may notice
- Ed02 on the display and the batch stopped
- Drum slowing or coasting to a stop during spin
- The message appearing at the start of braking
- A machine that runs light loads but stops on heavy ones
Possible causes
Listed in UniMac's documentation
- High line voltage at the washer
- Voltage spikes on the supply circuit
- A motor returning energy to the drive while braking a heavy load
- A drive board that misreads the bus voltage
Other likely causes — what usually sits behind error code Ed02 on this control. A technician confirms which one it is before any part is replaced.
- A building transformer tap or utility voltage that sits high during off-peak hours
- Large equipment elsewhere on the feeder switching off and sending a spike down the line
- A brake or deceleration ramp that is too short for a full-weight load
Safe checks before calling for service
- Power the machine down and leave it off for a few minutes.
- Have a qualified person check the voltage at the disconnect, since this is not a job for laundry staff.
- Try a lighter batch and see whether Ed02 returns.
- If it does, note the load weight, the cycle step and the time of day for the service call.
How a technician diagnoses error code Ed02
- Read the code history and note at which spin step Ed02 occurs.
- Measure incoming line voltage at the disconnect and at the drive during the day, comparing it with the machine's rating plate.
- Check for supply spikes or shared loads switching on the same feeder.
- Review the spin ramp and braking settings that affect regenerative energy.
- Replace the drive only after supply and load conditions are ruled out.
- Measuring line voltage at the disconnect means working on live 208 to 240 V or higher terminals.
- Drive capacitors can hold charge after power-off, so opening the drive is a hazard.
- Judging whether the bus reading is true or false takes a meter and the maker's drive reference.
Technical reference
- Document
- Washer-Extractor Programming CHM495R_SVG, Part No. F8208501ENR10, March 2017, Error Codes (pp. 36-37)
- Maker documentation
- UniMac owner support
- Edition
- Part No. F8208501ENR10, March 2017
- Models / control
- CHM495R family washer-extractor front-end control (20-100 lb)
- Section
- Error Codes table, pp. 36-37 (E Pr only on Design 1 models; Ed01-Ed11 on Design 2 and 3 models)
- Checked
- October 2026
We use the maker's document to read the code and do not reproduce it. Always confirm the complete model and control before applying these steps.
Related UniMac industrial laundry error codes
Does a high bus mean the drive is damaged?
No. It means the drive protected itself. The cause is usually the supply or a heavy load, though the drive board is checked last.
Why does a light load help?
A lighter drum stores less energy, so less is returned to the bus during braking. It is a way to separate load from supply.
Is Ed02 the same as Ed10?
No. Ed10 is a low bus dip that lets the batch continue. Ed02 is a high reading that stops it.
Need help with UniMac error code Ed02?
A technician confirms the cause on site and gives you the price in writing before any work starts.