: Turn on the Overvoltage Stall Prevention parameter ( L3-04 ).
: In systems where external safety devices are not used, factory-installed jumpers must be present between H1-HC and H2-HC. If these jumpers are loose or missing, the drive will default to a Baseblock state.
Yaskawa drives often use a detachable option card (PG Card) to interface with the encoder.
on a Yaskawa drive (most commonly the GA800 , GA500 , U1000 , or Z1000 series) indicates a Current Offset Fault . This is a hardware-related error, meaning the drive’s internal current sensor (CT) is detecting an abnormal offset when no current should be flowing.
The internal contacts of the safety monitoring relay may be welded shut or failing to respond simultaneously. yaskawa error code h66
This comprehensive troubleshooting guide explains why the H66 fault triggers and provides exact, actionable instructions to resolve it on your Yaskawa AC Drives . What is Yaskawa Error Code H66?
In massive automated systems, significantly different cable lengths between the relay and the two input channels can introduce enough propagation delay to cause a timing mismatch. 3. Faulty External Safety Devices
If you encounter the H66 error, follow this systematic approach to identify and resolve the conflict:
: The dynamic braking circuit cannot burn off the regenerative energy. : Turn on the Overvoltage Stall Prevention parameter
Upstream protection devices, like fuses or circuit breakers, may have tripped or failed on a single phase. Step-by-Step Troubleshooting Guide Check Input Voltage:
This determines if the drive coasts to a stop, ramps to a stop, or continues running when a fault occurs.
: Verify that all emergency stop buttons are released and safety gates are closed.
Power down the drive completely and wait for the "Charge" LED to turn off. Remove and re-insert the . Yaskawa drives often use a detachable option card
Ensure that all are grounded properly on the controller side.
Replace the Feedback Option Module with a known working spare.
Confirm that parameters related to external options (typically those starting with F1 or H1 ) are correctly set to recognize the hardware you have installed.
Sometimes, a minor electrical spike can create a temporary communication error. Turn off the main input power to the drive.
Place ferrite cores on encoder cables and install line reactors on the AC input to reduce electrical noise.
Last updated: October 2025