20ma output testing, Figure 4.1, 20ma testing – RLE LD5100 User Manual

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H A P T E R

HAPTER

4-20

A O

UTPUT

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.

Remove the two position plug from TB6.

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.

Reinstall the plug on TB6.

With the system on and no alarms present,

measure the DC voltage across the

resistor. A value of 0.8VDC should

operation.

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.

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.

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.

Remove the resistor from the plug and reattach any wires as necessary.

Figure 4.1 4-20mA Testing