Originally Posted by valentine
Thanks Mark. appreciate your inputs. We suspect some fault on the blower unit & have checked same. However same appears to be very free & bearings ok & temperature of bearings ok during running. as motors have been reconditioned - we are trying to figure out if the motor is the problem or the blower is the problem. Until we get a new motor - we are unable to determine this. We are planning to change the bearings of the blower as well. appreciate if u could revert as to which would be the best motor to use in this case if we change the bearings of the blower first - the motor drawing 2 amp or the 8 amp at no-load stage. This motor drives the ac blower of a accomoadtion ac unit of a sea going vessel & runs 24 x 7 for 365 days. Kindly revert with your inputs. Also kindly rvert as to what would be the ideal insulation values??
thanks / valentine
I have to ask, when you serviced the fan you took the sheaves off both the fan and the motor, are you certain that you put them back on correctly. If you didn't this would explain the high current draw under load, you have sped the fan up resulting in moving more air, just an idea.
As for testing the motors, measure the resistance of the field windings, each set of windings should be close to each other and have low ohms readings. I would select the motor with the most consistant low readings field windings to field windings.
An excerp from a motor testing article http://www.gainesvilleindustrialelectric.blogspot.com/
"To test the windings, use an ohmeter. Make sure any jumpers for voltage selection remain connected. For a nine lead, dual voltage motor connected for 480 volts, these would typically be the 4-7, 5-8, and 6-9 connections. Measure the resistance from 1-2, 2-3, and 3-1. The resistance readings should be between 1-2% of each other - in other words, BALANCED! There is no way to tell how much resistance you should get, but it is typically low. Realize that you are testing with a DC battery. Therefore, you are reading the resistance of the copper wire. In many cases, this will look like a short circuit. GOOD! It's when it doesn't look like a short circuit that you have problems. As long as the readings are low and balanced, you're ready to go to the next step. I can't tell you how many motors are brought to us because "the windings are shorted." Don't make that mistake."
Unless you have a megger you will not be able to test the insulation quality of the motors.