MORLEY ZX10Se Installation Manual download pdf (Page 64)

ZX Fire Alarm Control Panels MORLEY-IAS

Commissioning Manual Document No. 996-175-000-3, Revision 3 Page 59

16 Supplementary Information

 The control panel continually checks the wiring to determine if any external wiring has become short

 An indication of an earth fault is given by amber LED Indicators on the panel front. The earth point is

ith a ‘negative’ or ‘positive’ sign on the alphanumeric display.

 For example:







16.1 Locating Earth Faults

circuit to earth.

normally maintained at 1V above the battery negative terminal. The polarity of the fault will be

indicated w









ing

 Earth faults can appear on the following external cables:

1. S

2 Detector circuit loop wiring

 It is also possible to use a dc voltmeter in conjunction with a working panel to find out which circuit is

shorted to earth. This is particularly useful if the fault is past a loop isolator, as this type of fault can

often not be detected by a resistance check at the end of the loop.

 The following method describes how to locate this fault by disconnecting the external wiring.

1. Measure the voltage from the battery negative input to the supply board earth input. On a healthy

system, this will read approximately 1V.

2. If the voltage is less than 0.3V, the panel will register an earth fault to negative.

3. If the voltage is more than 1.5V, the panel will register an earth fault to positive.

4. Each of the external cables can be disconnected in turn while monitoring this voltage. As soon as the

faulty wiring is disconnected, the voltage will return to 1V. This identifies which cable is shorted to

earth.

The panel will normally continue to work with a single earth fault on the system. The fault, however,

should be rectified as soon as possible.

Locating the

Earth fault

 Most earth faults are found by performing resistance measurements on the cables before connect

them to the panel.

ounder circuit wiring

3. Auxiliary 24V output feed.

Please take great care not to disconnect any of the internal board-to-board connections

while the panel is powered up, otherwise damage may be caused to the circuits!

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MORLEY ZX10Se Installation Manual Page 64

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