Detnov CAD-250, Руководство по установке

Страница: 33 / 84

33
ENG
3.8.4. Checking the loop
To check the loop wiring, WITHOUT CONNECTING THE LOOP TO
THE CONTROL PANEL, carry out the following steps:
1. Disconnect the loop from the control panel at
both ends.
2. If you do not use isolators and your facility does
not use the connection in isolator mode, you can
measure the resistance of both lines simultaneously.
The measured value cannot exceed 44 ohms
3.
If the detectors use isolators, you will only be
able to measure the resistance of the positive pole.
The measured value cannot exceed 22 ohms.
S+
S-
R+
R-
S+
S-
R+
R-
LOOP
LOOP
S+
S-
R+
R-
S+
S-
R+
R-
LOOP
LOOP
4. Use a multimeter to check that there are no
leakages between the screen cable and the positive
(+) of the cable or the negative (-) of the cable.
5.
If the measurement shows a resistive value of
less than 1 megohm, it is possible that there is a
leakage.
Check the mesh voltage with respect to the neutral or
alternating voltage phase. Under no circumstances
must it have voltage.
Any leakage must be resolved before continuing
with the system start-up. The sectioning of the
facility in sections of 50% of the run may help to
effectively locate the problem.
No leakage of the mesh to earth, to the cabinet of the
control panel or any other than the one established
on the loop card is acceptable.
Once the previous checks have been carried out, reconnect the loop to
the control panel and check that the control panel is not showing any
fault.
Ω
S+
S-
R+
R-
S+
S-
R+
R-
LOOP
LOOP
STEP 1
Disconnect it on the
control panel
STEP 2
Loop resistance test
without isolators
STEP 3
Loop resistance test
with isolators
STEP 4
Leakages between
mesh and (+)
and (-) poles
STEP 5
Leakages between
mesh and earth / L / N
Ω
S+
S-
R+
R-
S+
S-
R+
R-
LOOP
LOOP
Ω
S+
S-
R+
R-
S+
S-
R+
R-
LOOP
LOOP