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System Performance with Advanced Microprocessor Controls
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4.4 Load Control Features
4.4.1 Short Cycle Control
The control system monitors the compressor and prevents it from turning on within 3 minutes of
being turned off. If this (on, off, on) occurs too often, 10 times in one hour, a Short Cycle alarm could
occur.
4.4.2 Sequential Load Activation Control
The control allows only one load output to be energized at a time on a restoration of power or micro-
controller reset. Each additional load output will be activated at one second intervals until desired
operating conditions have been met.
4.5 Additional Features
4.5.1 Connecting the Analog Sensors
The sensor inputs are factory set to accept a 4 - 20 mA signal. However, the inputs can be changed by
removing the appropriate jumpers on the control circuit board. See Table 14, Figure 5 and
Figure 6.
The user supplied analog sensors MUST have their own power supply. To reduce the effects of inter-
ference from any noise source, the sensor input wiring should be shielded twisted pair and the shield
tied to earth ground at one end.
Analog input terminals for field connections are factory wired to the microprocessor board if specified
when ordered. Eight terminals are located in the field wiring compartment of the unit. Wire sensors
to the terminals as follows:
Consult your Liebert supplier for a field installation kit to add these connections after unit delivery, if
required.
Table 14 Analog input terminals
Terminal Signal
41 Input #1 (+)
42 Input #1 (–)
43 Input #2 (+)
44 Input #2 (–)
45 Input #3 (+)
46 Input #3 (–)
47 Input #4 (+)
48 Input #4 (–)
Table 15 Additional connections available after unit delivery
Input #1 Input #2 Input #3 Input #4
4–20 mA Jumper P50.1 & 2
and P50.3 & 4
Jumper P50.5 & 6
and P50.7 & 8
Jumper P50.9 &10
and P50.11 & 12
Jumper P50.13 &14
and P50.15 & 16
0–5 VDC Jumper P50.1 & 2 Jumper P50.5 & 6 Jumper P50.9 & 10 Jumper P50.13 & 14
0–10 VDC NO Jumper
on P50.1 & 2
and P50.3 & 4
NO Jumper
on P50.5 & 6
and P50.7 & 8
NO Jumper
on P50.9 &10
and P50.11 & 12
NO Jumper
on P50.13 & 14
and P50.15 & 16