Problem:
Due to the Modbus adaption of the VFDs operating belt driven fans, Broken Belt Detection has been implemented on Symbio 700 and 800 units. "Broken belt detection” is where if the motor throws the belt and isn’t doing any work, the VFD can set an alarm and drop the VFD's run status. If you have determined that belts are aligned and properly tightened and getting nuisance alarms, it is recommended that you check and adjust the following parameters.
Most technicians have found that setting parameter 22-61 from 10% to 5% resolves the Broken Belt Alarm from reoccurring.
Default TR150 Settings:
22-60 “Broken Belt Function” set to [2] Trip for Belt Driven Fans (Set to [0] for DDP).
22-61 “Broken Belt Torque” set to 10%— this is the default, you may need to adjust this later.
22-62 “Broken Belt Delay” default is 60s. Motor ramp up time, 3-41 (30s) gives the motor time to ramp up to speed and will help avoid nuisance warnings while the motor is ramping up to speed.
How to determine proper setting for parameter 22-61, if you are getting nuisance alarms.
Navigate to Parameter 16-22 Torque %. What this does is display what the torque percent of the motor is at that moment. If you ramp the motor up and down you can watch this % change, then you want to set 22-61 a little BELOW the typical normal value of motor torque % so that it will trip if a broken belt condition occurs. Watch it under a few different load conditions and speeds and see what the normal values are.
WARNING:
Information in this article is intended for use by individuals possessing adequate backgrounds of electrical and mechanical experience and who comply with all federal, state, and local laws, rules, orders, or regulations related to the installation, service, or repair of a heating or central air conditioning product. Any attempt to install, service, or repair a heating or central air conditioning product may result in personal injury and/or property damage. The manufacturer or seller cannot be responsible for the interpretation of the information contained herein, nor can it assume any liability in connection with its use.