ABB ACS560 Warning A5EA Measurement Circuit Temperature
Staring at the A5EA warning on your ABB ACS560 VFD? This guide explains the internal temperature measurement fault, hardware troubleshooting steps, and how to resolve it.
When operating an ABB ACS560 drive, you might encounter specific internal warnings that don't point to the motor or the load, but to the drive's own health. One such critical alert is Warning A5EA: Measurement circuit temperature.
Unlike a standard "Overtemperature" alarm (which means the drive is simply too hot), the A5EA code indicates a failure in the logic the drive uses to measure temperature. In short: the drive's thermometer is broken. Because the drive can no longer safely monitor its internal heat, this warning is a serious precursor to a total hardware lockout. Here is how to diagnose and handle it.
What is the A5EA Warning?
The ACS560 uses internal thermistors and sensing circuits to monitor the temperature of the IGBTs (Insulated Gate Bipolar Transistors) and the Control Unit. The A5EA warning triggers when the CPU receives a signal from these sensors that is "out of range"—either far too high, far too low, or completely missing.
Common Causes of A5EA
Since this is an internal measurement fault, the causes are almost always hardware-related:
- Control Board Glitch: A temporary software hang-up in the analog-to-digital converter.
- Loose Internal Ribbon Cables: Vibration in the cabinet has loosened the connection between the Power Unit and the Control Unit.
- Failed Temperature Sensor: The internal thermistor on the power module has failed (opened or shorted).
- Extreme Environmental Conditions: Operating the drive in temperatures far below freezing or in highly corrosive environments that have damaged the PCB traces.
Step-by-Step Troubleshooting Guide
1. The "Cold Boot" Reset
Before assuming the hardware is dead, perform a total power discharge. This can clear "latch-up" conditions in the sensing circuitry.
- Turn off the main AC supply.
- If the Control Unit is powered by an external 24V supply, turn that off as well.
- Wait 10 minutes until the display is completely dark.
- Restore power. If the A5EA warning disappears, it was likely a transient electrical glitch.
2. Inspect Internal Connections
If the warning persists, the communication between the "Brain" (Control Board) and the "Muscle" (Power Module) may be interrupted.
- Remove the drive cover (after ensuring it is de-energized).
- Locate the ribbon cables connecting the control board to the power module.
- Unplug and re-seat these cables firmly. Check for any signs of corrosion or "soot" on the pins.
3. Check Ambient Temperature Range
If your facility is extremely cold (below -10°C or 14°F), the measurement circuit may fail to register a valid starting temperature, triggering A5EA. Ensure the cabinet environment is within the drive's specified operating range (usually -10°C to +40°C).
4. Verify Drive Hardware (The Replacement Stage)
If re-seating the cables and power cycling do not work, you are likely dealing with a permanent hardware failure.
- The Control Unit: The sensing logic on the CCU (Control Board) may be damaged.
- The Power Module: The thermistor embedded in the IGBT module may be faulty.
In the ACS560 series, these sensors are generally not field-replaceable. You will likely need to replace the Control Unit or the entire Power Module. Contact your local ABB service partner with the drive's serial number for a hardware assessment.
Summary Checklist
| Step | Action | Goal |
|---|---|---|
| 1 | Power Cycle (10 Mins) | Clear transient logic errors. |
| 2 | Reseat Ribbon Cables | Restore connection to internal sensors. |
| 3 | Check Environment | Ensure temp is not below -10°C. |
| 4 | Contact Support | Identify if the Control Board or Power Unit needs replacement. |
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