Under normal conditions, for the self-lubricating bear- ing, the rate of temperature rise should be from 20° to 25° F (11° to 14° C) during the ®rst 10 minutes after starting up and approximately 40° F (22° C) over 30 minutes. The rate of bearing temperature rise is a function of the natural ventilation and operating conditions.
When the rate of bearing temperature rise is less than 2° F (1.1° C) per half-hour, the bearing temperature is considered to be stabilized.
If the total bearing temperature exceeds 195 F (91 C), the motor should be shut down immediately.
3.Any abnormal noise or vibration should be immediately investigated and corrected. Increased vibration (with the motor uncoupled from its load) can indicate a change in balance due to a mechanical failure or loose rotor part, a stator winding problem, a foundation problem, or a change in motor alignment.
4.Verify that the magnetic center indicator aligns with the shaft.
Initial Coupled Start-Up Ð After initial uncoupled start-up, take the following steps to ensure safe coupled operation:
1.Follow the procedure stated in the General Maintenance, Chiller Alignment section to align the motor to the driven chiller.
2.Prepare the coupling for operation according to the Disc Coupling Installation and Alignment instructions, this page. Note any match marks on the couplings and assemble ac- cordingly. For sleeve bearing motors, verify that the cor- rect limited end ¯oat coupling has been installed. The end ¯oat limits can be found on the certi®ed drawing.
3.Ensure that all personnel are at a safe distance from ro- tating parts. Start the motor in accordance with instruc- tions supplied with the motor control.
4.If the motor rotor fails to start turning in a second or two, shut off the power supply immediately. This can result from:
a.too low a voltage at the motor terminals
b.the load is too much for the rotor to accelerate
c.the load is frozen up mechanically
d.all required electrical connections are not made
e.single-phase power has been applied
f.any combination of the above.
Investigate thoroughly and take corrective action before attempting a restart.
5.Carefully observe the vibration of the bearing housing and any abnormal noise generator. Note that coupled motor vibration may not be the same as uncoupled vibration amounts. If coupled vibration is excessive, recheck the mounting and alignment.
6.Carefully observe the bearing temperature rise and the movement of the oil ring.
If the bearing temperatures rise and motor operation ap- pears normal, operation should continue until the bearing temperatures stabilize.
7.If possible, check the motor line currents for balance.
Note that each start time an induction motor starts, it is subjected to the full inrush of current along with heating of the stator and rotor windings. Each acceleration and re- peated start can produce more heat than is produced and dis- sipated by the motor under full load. The starting duty for which the motor is designed is shown on a nameplate mounted on the motor. Do not exceed this amount if long motor life is expected.
Abnormally low terminal voltage, excessive load torque, and/or excessive load inertia during motor start-up can cause lengthened acceleration times during which rotor ventilation is reduced. This can cause rotor damage or can lead to short- ened rotor life.
The temperature rating of the motor is shown on the main nameplate as a temperature rise above an ambient tempera- ture. If there is a service factor, it is also shown. If the motor temperature switch opens, investigate the situation before at- tempting to continue operation.
If the motor is a TEWAC (Totally Enclosed Water-to-Air Cooled) design, the maximum inlet water temperature and the water ¯ow rate or gpm (gallons per minute) at the air cooler must be as shown on the certi®ed drawing. Other- wise, the discharge air temperature from the cooler (actually the ambient air for the motor as shown by the main name- plate) could be too high for the motor to properly cool.
Disc Coupling Installation and Alignment Ð Be- fore installing the disc coupling, inspect it for any signs of damage during shipment. Check that all parts are available, as ordered. Cradle or support the coupling components dur- ing handling to avoid damage. Wrap the components for pro- tection. Keep ¯anges free of nicks and burrs. Read all the instructions and review this procedure before beginning the actual installation. Some steps apply only to certain types of couplings (e.g., high speed coupling).
Use only the bolts and nuts supplied by the coupling manufacturer.
1.Installing the Coupling Hubs (Keyed Mounting).
a.Check the hub bore and shaft for nicks and burrs; dress if necessary.
b.For taper bores, check the ®t of the bore to the shaft.
c.Fit keys precisely to the keyways in the shaft and hub. Each key should have a tight ®t on the sides with a slight clearance on top. To maintain dynamic balance, the keys should ®ll the keyways exactly and not be too short or too long.
d.Clean the hub bore and shaft.
e.Heat the hub to expand the bore. DO NOT allow the hub temperature to exceed 600 F (300 C). DO NOT apply an open ¯ame to any part of the coupling. Car- rier recommends using an oven to heat the hub.
To avoid the risk of explosion, ®re, or damage to the coupling and equipment and/or injury to per- sonnel, do not use an open ¯ame or oil bath to ex- pand the hub. If heat is used at anytime for instal- lation, DO NOT ALLOW the hub temperature to exceed 600 F (300 C).
f.Place the hub in the proper position on the shaft. Hold the hub in place as it cools. For tapered bores, verify the hub advance and install the shaft retaining nut.
