208 motor
- Thread starter normbac
- Start date
- Status
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
080702-0756 EST
Any motor can be run at any voltage and frequency that will not overheat the motor and will supply the required output torque at required speed with the required speed regulation.
For an AC induction motor the speed is relatively constant at a fixed frequency. However, speed does drop as load is increased.
Output shaft mechanical power has to be supplied from input electrical power. Input power is output power plus motor losses. On this basis as an approximation as voltage goes down current has to increase. As current increases motor I^2*R losses increase. On the other hand as voltage goes up magnetic and eddy current losses increase.
If a motor is lightly loaded mechanically you will be able to go to lower input voltages. But other factors might prevail.
A compressor is a heavy load application. If the motor is slow to start, in other words does not just jump to full speed, then I suggest you have a problem. If you could get information from the motor manufacturer on a maximum motor surface temperature, then under load you could determine if the motor is getting too hot.
Are you saying that line voltage is 206 unloaded and 195 at maximum load, then your drop is 11 V or 11/206 or about 5% from the load. Less drop would be better since you are on the low side of 208, but this might be OK. The startup and temperature factors are your primarily concern.
.
Any motor can be run at any voltage and frequency that will not overheat the motor and will supply the required output torque at required speed with the required speed regulation.
For an AC induction motor the speed is relatively constant at a fixed frequency. However, speed does drop as load is increased.
Output shaft mechanical power has to be supplied from input electrical power. Input power is output power plus motor losses. On this basis as an approximation as voltage goes down current has to increase. As current increases motor I^2*R losses increase. On the other hand as voltage goes up magnetic and eddy current losses increase.
If a motor is lightly loaded mechanically you will be able to go to lower input voltages. But other factors might prevail.
A compressor is a heavy load application. If the motor is slow to start, in other words does not just jump to full speed, then I suggest you have a problem. If you could get information from the motor manufacturer on a maximum motor surface temperature, then under load you could determine if the motor is getting too hot.
Are you saying that line voltage is 206 unloaded and 195 at maximum load, then your drop is 11 V or 11/206 or about 5% from the load. Less drop would be better since you are on the low side of 208, but this might be OK. The startup and temperature factors are your primarily concern.
.
- Location
- Illinois
- Occupation
- retired electrician
That nameplate means that the motor is suitable for operation at any nominal system voltage from 208 to 240. The operating voltage of the system may well be outside of that range. Most motors are suitable for operation at plus/minus 10% of the nominal system voltage, making that motor suitable for operation at voltages between 187 and 264.
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
The motors I have installed for 208 volt systems are rated 200 volts, 240 are rated 230 volts, 480 are rated 460 volts. This is to allow for some voltage drop. Motors are designed to operate +/- 10% of rated voltage. I try to keep the voltage no less than the rated voltage, no more than 5% drop.
- Status