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7.2 Test procedure for detection lines
Before powering the control unit lines, check the following values:
A DIGITAL MULTI METER IS REQUIRED
Line resistance
The direct current resistance of the negative wire of the loop SHALL NOT exceed 20 Ohm.
The measurement must be performed by disconnecting the channels "A" and "B" from the LIB Multi meter probes
are to be connected to the Negative wire terminals.
To have the total loop wire resistance, multiply by 2 the value read on the Negative side.
Line insulation
Place between (+) and (-) of line through a tester, with sensors or modules installed and check the following:
OPEN
Test 1:
Connect: Tester (+) / Line (+) and Tester (-) / Line (-)
Check: Resistance: 1 ... 1.3 M Ohm
Test 2:
Connect: Tester (+) / Line (-) and Tester (-) / Line (+)
Check: Resistance: 0.7 ... 0.9 M Ohm
Screen shield insulation from the cable/line
Place a test probe of the tester on the line cable screen and the other test probe on the positive cable (+) of the
same line. The resistance measured must be higher than 15 ... 20 M Ohm, better if "infinite".
Perform the same operation between the line screen and negative cable (-). Check that also in this case the
resistance is higher than 15 ... 20 M Ohm.
Earthing /lines insulation
Place a test probe of the tester on the system earthing and the other test probe on the positive cable (+) of the
line; the resistance measured must be higher than 15 ... 20 M Ohm, better if "infinite".
Perform the same operation between the earthing and negative cable (-) of the line. Check that also in this case
the resistance is higher than 15 ... 20 M Ohm.
Earthing /cable screen insulation
Place a test probe of the tester on the system earthing and the other test probe on the cable screen; the
resistance measured must be higher than 15 ... 20 M Ohm, better if it is "infinite".
Line voltage
With the sensors/modules line connected, the line output voltage must be 24 Vcc without the device query
(no programmed Point). A voltage much lower than 14 Vcc indicates a connection reversed on detector or modules.
M-167.1-MA1000-EN / 02.2023
Positive
Side B
Negative
Side A
OR
OR
CLOSED
MA-1000
27
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