Precautions After The Motor Has Been Shut Down for A Long Time

Date: 2021-12-23     From: Longding     Author: admin

The insulation performance of the motor after a long period of the shutdown may be affected by air humidity, dust, and dirt. It is necessary to measure the insulation resistance value before resuming operation to ensure that the motor can be started correctly. In addition, bearings, cooling systems, and slip ring devices also need to check the lubricant, air circulation, and carbon brush wear before restarting the motor to keep your motor performance in good condition. Check the following steps before starting the motor.

1. Stator winding insulation resistance measurement

Use an insulation resistance meter to measure the insulation resistance, the test voltage is 1000 VDC, the test time is 1 minute, and then the insulation resistance value is recorded. Before performing an insulation resistance test, the following measures must be taken:

A. Make sure that the auxiliary connections of the current transformer (CT), including the backup coil, are not open.

B. Verify that all power lines are disconnected.

C. Verify that the motor frame and untested stator windings are grounded.

D. Measure the winding temperature.

E. All resistance temperature sensors are grounded.

F. The possible grounding of the voltage transformer must be removed.

2. Rotor winding insulation resistance measurement

Use an insulation resistance measuring instrument to measure the insulation resistance of the rotor winding. The test voltage of the rotor winding is 1000 VDC. Matters needing attention and measures:

A. Verify that all power lines are disconnected from the power source.

B. Check whether the slip ring device connection cable is disconnected from the power supply.

C. Check whether the equipment frame and stator winding are grounded.

D. The shaft is grounded.

E. Check the measuring device.

F. Measure the temperature of the stator winding and use it as a reference for the temperature of the rotor winding.

3. Bearing inspection

A. Bearing type: plain bearing

The sliding bearing oil sump and possible oil supply system have been filled to the correct oil level with the recommended lubricating oil. The fuel supply system is turned on.

B. Bearing type: rolling bearing

Rotate the rotor by hand to confirm that the bearing does not make any abnormal noise. A simple lever is required to rotate a rotor equipped with a sliding bearing.

4. Cooling system inspection

Check whether the connection is tight and whether there is a leak in the system. Check the coolant and check whether the air circulation is blocked according to the actual situation.

5. Slip ring device

A. Track the wear of the carbon brushes and replace the carbon brushes before the wear level reaches the limit.

B. Check whether the brush produces sparks.

C. Ensure that the surface of the slip ring is smooth.

D. Check whether the slip ring housing is tight. Do not allow water, grease, lubricating oil or dust to enter the housing.