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3.5.5 Thermal switch connection

You might wish to wire the motor’s thermal switch contacts (normally closed), using a relay, to a digital input on connector X3 (see section 3.3.1). Using the Mint WorkBench Digital I/O tool, the input can be configured to be the motor trip input. This allows the MicroFlex e100 to respond to motor over-temperature conditions. The Mint keyword MOTORTEMPERATUREINPUT can also be used to configure a digital input for this purpose. A typical circuit, using DIN1 as the input, is shown in Figure 9.

 

A

motor

 

thermal

 

switch

B

 

+24VDC

 

0V

 

 

 

 

 

Separate customer supplied 24VDC supply

‘X3’

DIN1+ 16

Relay

DIN1-

6

 

+24VDC

0V

Customer supplied 24VDC supply

Figure 9 - Motor thermal switch circuit

CAUTION: The 24VDC power supply connected to the thermal switch must be a separate supply as shown in Figure 9. Do not use the 24V supply used for the drive enable signal, or the internally generated supply (if present). The thermal switch wires often carry noise that could cause erratic drive operation or damage. The thermal switch contacts must never be wired directly to a digital input.

The separate 24VDC supply used for the thermal switch may also be used for the motor brake circuit (section 3.5.6).

MN1942

Basic Installation 3-21

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Baldor E100 manual Thermal switch connection, Motor thermal switch circuit