Table of Contents
Advertisement
16.0 Supplementary Information
16.1
Locating Earth Faults
•
The control panel continually checks the wiring to determine if any external wiring has become short circuit
to earth.
•
An indication of an earth fault is given by amber LEDs on the panel front. The earth point is normally
maintained at 1V above the battery -ve terminal. The polarity of the fault will be indicated with a "-ve" or
"+ve" sign on the alphanumeric display.
•
For example:
•
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.
16.1.1
Locating the Earth fault
•
Most earth faults are found by performing resistance measurements on the cables before connecting them
to the panel.
•
Earth faults can appear on the following external cables :
-
NAC circuit wiring
-
Detector circuit loop wiring
-
Auxiliary 24V output feed.
•
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.
-
Measure the voltage from the battery negative input to the supply board earth input. On a healthy
system, this will read approximately 1V.
-
If the voltage is less than 0.3V, the panel will register an earth fault to negative.
-
If the voltage is more than 1.5V, the panel will register an earth fault to positive.
-
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.
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!
16.2
Overriding Delays on Individual Outputs
•
The panel allows delays to be set on individual outputs, as required.
•
It is recommended that a facility is provided, in the installation, to override any delayed circuits.
•
This can be achieved in either of two ways as follows:
-
Assign a manual call point to a zone in which all outputs act immediately.
-
Allocate all delayed outputs to a system event. Arrange a manual call-point to generate this event.
•
If a specific manual call-point (pull station) is to be used for this purpose, it may be desirable to locate the
call point either adjacent to the control panel or on a main exit route and label it accordingly.
© 2002 Radionics
D8024/D10024A Operation and Installation Guide
Page 53
D8024/D10024A
Supplementary Information
50616B
Advertisement
Table of Contents
