An Overtemperature fault is a common in Variable Frequency Drives and can be found in numerous applications. The fault occurs when the heatsink on the drive exceeds a measured allowable set temperature.
The drive creates a fault condition to prevent internal component damage due to the excessive heat. It is commonly seen as a fault code of “H/S Overtemp”, “oH”, or “oT” depending on the manufacturer. Below are three common causes to this condition and what you can do to correct the issue:
Fan Failure
- When internal fans fail the heat rises quickly. There is typically a fan internal to the drive that can run on control power and if this gets disabled within the parameters it needs to be adjusted.
- If that doesn’t do the trick it may have an internal issue and it would need to be replaced.
- The airflow could be blocked. Ensure the vents are clear of any debris, especially if located in a particulate dirty environment, and that the drive was mounted with the proper space to vent per the manufacturer’s requirements.
- Panel mount VFD’s should be sized carefully as the heat output of other equipment can impact performance. Ensure panel cooling is functional.
Extreme Ambient Temperature
- Summertime can be hard on VFD’s, especially if they are exposed to higher-than-normal temperatures. Direct sunlight is a big factor and can event impact a VFD’s that are panel mounted.
- In these applications add additional heat sinks in the form of flanges that will help dissipate heat on the backside of the VFD. This is generally done before the VFD is installed to ensure the proper heat calculations were completed.
Excessive Motor Current
- There are a multitude of reasons that a motor pulls excessive current and when that happens the VFD will experience significant heat rise.
- Verify VFD parameters to ensure they align to the motor nameplate.
- Inspect cabling for signs of excessive heat. If the motor draws enough current to cause an overtemperature fault, it could damage the internal components or wiring of the device.
These three areas are great places to troubleshoot and understand why your VFD experienced an overtemperature fault. The team at EECO is here to serve you with VFD support and you can connect with us here to learn more.
Resources:
EECO Asks Why – 155 VFD Integration
EECO Asks Why – 110 VFD Applications
EECO Asks Why – 130 VFD Startup: What should I know
EECO Asks Why – 102 Integrating Mcirodrives with Ethernet/IP
What to consider with a starter to VFD conversion
