Schuch nD8700 Series Operating Instructions Manual page 8

5.1 Isolation measurement
For measuring the isolating resistance the test voltage must be put on between the outer conductor
and the earth conductor or between the neutral conductor and the earth conductor only.
After finishing the isolation test the conductor between the mains and the light fitting must be
reconnected safely. Before starting operation the connection of the neutral conductor must be safe for
avoiding any damage whatsoever of the electronic control gear caused by any inadmissible excess-
voltage in case of an unbalanced mains load. (see section 5.2)
5.2 Electronic gear in 3-phase-operation
The diagram shows the wiring for light fittings or light fitting groups in 3-phase circuits and with a
common neutral conductor N. If the common neutral conductor is interrupted and voltage is present,
then light fittings or groups of light fittings may be exposed to unacceptably high voltages and
consequently the electronic gear may be destroyed.
Light fittings with electronic gear
5.3 Testing the restricted breathing
The test of the restricted breathing of the light fitting must be carried out after installation and at regular
intervals. For this purpose, the light fitting is provided with a test port, which consists of an Ex cable
gland which is locked by a closing plug.
For testing, a negative pressure is to be generated in the light fitting via the test port. Under constant
temperature conditions, the vacuum must exceed a predetermined minimum value after a specified
waiting time has elapsed.
According to EN/IEC 60079-15:2019, section 12.2.2.1.2, three test methods can be used:
Underpressure
at the beginning of the test
Waiting time
Minimum underpressure
after waiting time has elapsed
 After completing the test, make sure that the closing plug is inserted back into the Ex
! cable gland and the pressing screw is tightened properly (Torque see section 3,
Technical Data).
10/2022 L-01424-4-14
•
OK
Method 1 Method 2
3 kPa 0,3 kPa
(30 mbar) (3 mbar)
14 s 14 s
2,7 kPa 0,27 kPa
(27 mbar) (2,7 mbar)
8
fault
Method 3
0,3 kPa
(3 mbar)
90 s
0,15 kPa
(1,5 mbar)