NSC Sicherheitstechnik GmbH
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B01050 B01060 Operating Installation Manual Solution F1 20130814.doc
33719 Bielefeld
Version S040A13.08
Checking of earth fault
A constant voltage must not be measurable between potential earth and fire control panel
potential there
Voltage between PE / - accumulator
Ο
Ok
Ο
fault -> .............V
Voltage between PE / + accumulator
Ο
Ok
Ο
fault -> .............V
In case of an earth fault this has to be localised by disconnecting single cables in the fire control
panel. Then the earth fault has to be removed. The supervision of an earth fault can be
deactivated by system parameter 13.
Measurement of loop voltage and current
Dependent of the used multimeter the voltage and the current will vary differently. This is caused
by the modulated protocol between the FCP and the loop devices. For the measurement of the
current the loop has to be separated on one side in the FCP and on the other side the current has
to be measured on the ML+ or ML- wire. At the same time the loop devices have to be in the
quiescent state. Decisive for a faultless operation is the fact, that all loop devices are supplied by
a sufficient voltage (17V). The voltage drop on the cable has to be calculated form the quiescent
current and the cable resistance measured under point 4.2.
Loop card
Loop
Voltage
33V ± 3V
Quiescent
current
[mA]
Voltage drop[V]
(quiescent current x
cable resistance)
1
1
(ML-1-/ML-2-)
1
2
(ML-5-/ML-6-)
2
3
(ML-1-/ML-2-)
2
4
(ML-5-/ML-6-)
3
5
(ML-1-/ML-2-)
3
6
(ML-5-/ML-6-)
4
7
(ML-1-/ML-2-)
4
8
(ML-5-/ML-6-)
5
9
(ML-1-/ML-2-)
5
10
(ML-5-/ML-6-)
6
11
(ML-1-/ML-2-)
6
12
(ML-5-/ML-6-)
7
13
(ML-1-/ML-2-)
7
14
(ML-5-/ML-6-)
8
15
(ML-1-/ML-2-)
8
16
(ML-5-/ML-6-)
9
17
(ML-1-/ML-2-)
9
18
(ML-5-/ML-6-)
