I check with our supplier. they told me that we have to load on motor then only it will show correct rpm ( both low and high). what is the maximum load for this motor It is shoiwng 1.3 amp
DOES THE MOTOR HAVE A 2 SPEED switch, and what are you using it for? 1.3 amps has to be 120 volt. its probably a 2 speed motor without a switch. in that case it has to be under a load. if this helps you cant hear it change speeds, even under a load, i really need more info before i can help you. how are you checking the rpms? butch
The motor that you have must be a shaded pole motor with a “full-torque” connection and a “reduced-torque” connection. With either connection, the motor will run at nearly 1200 RPM (assuming 60 Hz) when it has no load. The load causes the motor speed to be reduced below 1200 RPM. With the “reduced-torque” connection, the load has more effect and the motor runs at a slower speed. The motor is designed to drive a fan. Fans have the characteristic that the torque required to drive them at any given speed is proportional to the square of the speed. A fan that requires 1/3 Hp at 1070 RPM would require 0.33 X 5252 /1070 = 1.64 lbs-ft of torque at 1070 RPM. At 800 RPM, the fan would require 1.64 X 800^2 / 1070^2 = 0.91 lbs-ft of torque. The horsepower required at 800 RPM would be 0.91 X 800 / 5252 = 0.14 Hp. The operating speed of the motor depends on the torque vs speed characteristic curves of the motor for the two connections intersecting the torque vs speed characteristic curve of the fan at the desired speeds. If it is the proper motor for the fan and the restriction of air flow corresponds to the design, the motor should operate at the design speeds. With any AC motor and particularly with this type of motor, it is difficult to estimate load from current. This type of motor is very inefficient. Even if you measure power, it will be difficult to estimate load.
