RLE Technologies LD5100, User Manual

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C
H A P T E R
C
HAPTER
0
4-20
M
A O
UTPUT
T
ESTING
The LD5100’s 4-20mA output is loop powered and tested by the manufacturer. The
manufacturer guarantees its performance upon delivery. Should the 4-20mA output need to be
tested in the field, follow these steps. The following procedure is performed with the cable
connected, unless otherwise indicated.
1
Remove the two position plug from TB6.
2
Remove any wires from the terminal and
install a 200Ohm resistor to TB6-2. Then
apply +24V to TB6-1 and ground of the
24V supply to the other side of the
resistor.
3
Reinstall the plug on TB6.
4
With the system on and no alarms present,
measure the DC voltage across the
resistor. A value of 0.8VDC should
register. This equates to 4mA, or normal
operation.
5
Remove the SeaHawk Leak Detection
Cable (SC) and wait for the unit to activate
its cable trouble alarm. Measure the DC
voltage across the resistor. A value of approximately 4.0VDC should be measured. This
equates to 20mA, or a fault alarm. Reconnect the SC cable.
6
Place water on the end of the SC cable. Measure the DC voltage across the resistor. The
value will be proportional to the length of cable measured by the LD5100. A value of
approximately 4.0V, which equates to 20mA, will be read if the length of the cable is
identical to the length read by the LD5100. Dry the cable.
7
Place water on the start of the cable. Measure the DC voltage across the resistor. A
measurement of approximately 0.8VDC, or 4mA, should be measured. This corresponds to
a leak at zero distance. Dry the cable.
8
Remove the resistor from the plug and reattach any wires as necessary.
Figure 4.1 4-20mA Testing