Water Detection Display; Figure 6 Connecting The Lt750 - Liebert Himod Operation & Maintenance Manual

4.5.2

Water Detection Display

The water detection display is designed to graphically display the location of water under a raised
floor when connected to an LT750 water detection system. The graphical floor plan screen shows a 30
x 16 grid. Each square represents one standard floor tile (approximately 2 ft. x 2 ft.).
Installation—LT750 DIP Switch Settings
Install the LT750 following the instructions in the LT750 user manual. The following additional
switch selections should be made when connecting to an Advanced Microprocessor control:
• DIP SW3-4 Off-(water alarm relay energizes for alarm)
• DIP SW3-5 Off-(cable fault relay energizes for alarm)
• Switch 1 - Off -(LT750 sources power for 4-20 mA loop)
Figure 6 Connecting the LT750
Physical Connections
Figure 6 shows the 4-20 mA output of LT750 connected to Analog Input #1 (41 and 42) on the exter-
nal inputs terminal strip. This strip is provided on units ordered with analog inputs. (If this strip is
not installed, there is a field installation kit available from your Liebert representative.)
The 4-20 mA output of the LT750 must be connected to the first analog input, as shown.
TB4 is the water detected relay output. It can be connected to any one of the four special alarm inputs.
TB5 is the cable fault relay output. It can also be connected to any one of the four special alarm
inputs.
Setup
(The following description assumes the wiring connections as shown in Figure 6.) First, verify that
special alarms 1 and 2 are ENABLED to either WARNING or URGENT type. Do this by selecting
VIEW/SET ALARMS from the Main Menu. Then, select SETUP ALARMS. Follow the instructions on
the display to select the required type for CUSTOM ALARM #1 and CUSTOM ALARM #2 if not
already set.
Next, select the alarm message for CUSTOM ALARM #1 and #2. From the Main Menu, select VIEW/
SET ALARMS. Then, select SETUP CUSTOM ALARMS. Then, select SETUP CUSTOM ALARM
TEXT. Define CUSTOM ALARM #1 to be CUSTOM 1. (CUSTOM 1 is the default message that will be
displayed if a message has never been programmed.) Next, select the text for custom alarm #2 to be
WATER UNDER FLOOR. Now, change the message CUSTOM 1 to LT750 CABLE FAULT. This is
done by selecting the CHANGE CUSTOM TEXT 1 menu item in the SETUP CUSTOM ALARMS
menu. Follow the instructions on the screen to change the message.
The slope and intercept values of Analog Input #1 are used to calculate the location of water. These
values should initially be set to zero. The default values are zero, but it may be a good idea to verify
those values. They can be viewed by selecting ANALOG/DIGITAL INPUTS from the Main Menu,
then SETUP ANALOG INPUTS.
See 3.4.6 - Setup Water Detect Floor Plan for more information.
32 System Performance with Advanced Microprocessor Controls
-
2
TB6
1
+
NO
3
TB5
2 NC
1
fault
C
NO
3
TB4
2
NC
1
water
C
LT750 Environmental Unit
4 1
4 2
4 3
4 4
4 5
4 6
4 7
4 8
2 4
5 0
5 1
5 5
5 6