Retrotec Blower Door - Manual (Page 55)

Page 55 of 87
©Retrotec Inc. 2015
8. Fan Troubleshooting
8.1 Retrotec 2000 series 120 Volt AC motors overheat and
shut off
There is a lot of variation from one motor to the next as they come from the manufacturer. Some motors heat up
more than others, in spite of undergoing the same manufacturing process. All motors are tested at Retrotec
facilities for 1.5 hours under full current and stress. The motors which shut off due to excess heat are rejected, and
sent back to the beginning of the production line. Some users, however, may still encounter problems in the field.
Below are some points that may be followed to remedy a specific problem.
Make sure the motor runs as close to full speed as possible. The faster it runs, the more air goes through the motor.
A rule of thumb is to have the Fan Pressure over 100 Pa and the motor running near full speed. The motor heats up
the most at ¾-speed where it draws 13 amps at 120 volts. At full speed the motor will draw less current!
Make sure the C8 Range Plate has the cooling ports in line with the ones on the motor cover. If the mounting
indicator sign is in the correct position, this will ensure the ports are fully open.
Ensure that the switch on the speed controller is in the off (0) position at the rocker switch, not just turned down. If
left on low speed with the blade not turning, the controller and the motor will be stressed.
The thermal breakers that shut down the motor are not adjustable. To learn when maximum heat is created, put a
current meter on the fan, and adjust the fan speed to see when it is pulling maximum current, and therefore
creating maximum heat.
More current = more heat.
More airflow through motor = less heat.
A more drastic solution is to change the blade or to cut a quarter inch off the blade tips and re-balance the blade to
reduce the load on the motor.
8.2 3300 High Power Fan will not control smoothly
Retrotec 3300 series variable-frequency fans require 100-280 VAC 50/60 Hz power in order to operate reliably.
Voltage drops due to line losses and fluctuations in AC power can be significant. The fans will not work at line
voltages of less than 95 VAC.
If the system will:
1. Not control smoothly
2. Slow suddenly
3. Stop completely
4. Produce less than 6,500CFM @100% speed
5. Multi-fan systems will oscillate, with fans running at varying speeds
The problem is likely that insufficient line voltage is arriving at the variable-frequency power supply.
To resolve the lack of smooth control issue
1. Use a 240VAC Stove or Dryer outlet or
2. Use 208VAC or
3. Reduce extension cord length on 120V circuits and/or use an industrial quality 12 gauge extension wire.