Power Supply And Input/Output Signal - Michell Instruments Liquidew I.S. User Manual

Liquidew I.S. User's Manual
1.4.2

Power Supply and Input/Output Signal

The terminal blocks for the power supply, signal input, signal output and alarm output
are located on the back panel of the control unit (as shown in Figure 9) .
• Power Supply
The Liquidew I.S. requires either 85 to 265 V AC or 10 to 72 V DC power
input, depending on the model ordered.
• Signal Input
There are two 4-20 mA signal input channels from the dew-point and
temperature sensors to the control unit. Both input channels are isolated by
built-in galvanic type I.S. barriers.
• Signal Output
There are two 4-20 mA linear signal output channels. The output channel 1
is used for the dew point, moisture or temperature signal, with confi gurable
ranges. Output channel 2 has a fi xed temperature signal and cannot be
confi gured.
There is one RS485 Modbus RTU digital communication port. Please refer to
Appendix B.
• Alarm Output
There are four alarm relays. Alarms 1 and 2 are Form C contacts rated 10A
/ 240 V AC or 8A / 24 V DC, non-inductive load. Alarms 3 and 4 are Form
A contacts rated 5A / 240 V AC or 4A / 24 V DC, non-inductive load. The
control actions and set points of these four alarms are user-programmable.
A fault alarm with adjustable set points is also included.
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