ABB AK102 User Manual page 23

6.3 Electrical Checks
Carry out the electrical checks detailed in Sections 6.3.1 and
6.3.2.
6.3.1 Power Supply Unit Output
Warning. This unit is part of the certified intrinsically
safe system. Appropriate safety precautions must be
taken to prevent any incendive electrical discharges in
the hazardous area when carrying out this task.
Testing the output may only be carried out with the
hazardous area cable disconnected.
1) Electrically isolate the PSU.
2) Remove the cover from the PSU.
3) Disconnect the output wires to the hazardous area at
terminals TB2+ and TB2–.
Warning. Ensure that
precautions are taken at all times when undertaking this
procedure.
4) Switch on the PSU and check that the output measures
350mA into a 14 load.
5) On completion of tests isolate the unit and reconnect the
output wires to the hazardous area.
proper electrical safety
6.3.2 Zener Diode Safety Barrier Devices
The zener diode safety barrier devices (MTL7755ac or
MTL7055ac) in the 6553 Display Unit are checked at the time of
manufacture. To ensure absolute safety when fitting a new
instrument, check that the barriers in the display unit are
properly earthed by carrying out a routine test before using the
analyzer system.
Warning .
• This unit is part of the certified intrinsically safe
system. Appropriate safety precautions must be
taken to prevent any incendive electrical discharges
in the hazardous area when carrying out this task.
• If these tests reveal a faulty zener barrier, the barrier
MUST be replaced by a new unit. The barrier is a
sealed unit and no repair is permitted. The correct
zener barriers are certified intrinsically safe and
conform to the ATEX Directive 9/94/EC, certificate
number BAS 01 ATEX 7217 (MTL 7755ac) or
BAS 99 ATEX 7285 (MTL 7055ac).
• Replacement Zenner barriers MUST be of the same
type.
6.3.3 Checking System Earth
Check that the resistance between earth terminals on the
analyzer system and the application plant system safety earth
does not exceed 1 .
6 SETTING UP
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