Section 4
Optional Accessories
Optional Accessories 4-1
MN409
The owner is responsible for conformance to national electric code and all other applicable local codes
and practices. Refer to Safety Notice in Section 1 of this manual.
Note: Motor is equipped with the following accessories only if ordered with the motor.
Winding Resistance Temperature Detector RTD
Purpose
To measure or monitor winding temperature during operation.
Principle of Operation
The RTD uses a wire wound in a flat ribbon coil. It is wound so that it is a non
−
inductive device. Its mode
of operation is that of a linear change in resistance with temperature.
Customer Interconnect
RTD leads are supplied in a separate conduit box. Leads are tagged and connected to a terminal block.
One side of the customer’s bridge circuit must be grounded. This can be done either at the motor
terminal box or at the instrumentation end of the circuit. Voltages that might appear on the circuit will then
be passed to ground.
Remarks
1.
Can provide either continuous temperature measuring or temperature monitoring.
2.
Needs a separately mounted control and power source to read temperature or to provide a means
for relay operation (for either alarm or motor shut down features. )
3.
Temperature can be monitored using an ohm meter or a resistance bridge and converting the
resistance to temperature.
4.
Will respond thermally to normal load and temperature changes, but not fast enough to provide
locked rotor protection.
Winding Thermostat
Purpose
To indicate the winding temperature has exceeded normal operating temperatures.
Principle of Operation
The thermostat uses a bi
−
metal snap action disc to operate a set of contacts. The operating temperature
is factory selected and non
−
adjustable. The contacts can be wired directly to a relay to provide either
alarm indication or motor shut down features. Means of temperature measuring or monitoring cannot be
provided with this device. Refer to lead tags tor voltage and current limitations of contacts.
Customer Interconnect
Leads terminate in a separate conduit box. Leads are tagged.
Remarks
1.
Cannot be used to measure or monitor temperatures.
2.
Can be directly wired to motor starter hold in coil relay to provide motor shut down due to excessive
temperature.
3.
Can be wired directly to an alarm circuit without the use of a separate relay.
4.
Can be used for AC or DC operation.
5.
The thermostat provides a thermally automatic reset feature. The snap action automatic reset
feature can cause difficulty in troubleshooting unless it is connected to a manual reset relay.
6.
Will respond thermally to normal load / temperature changes; however will not respond fast enough
to provide locked rotor protection.
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