GE Mark VIe System Manual page 154

6.9.1 Power Wiring and Circuit Checks
The 125 V dc supply must be installed and maintained so that it meets requirements of IEC 61010-1 cl. 6.3.1 to be considered
Not Hazardous Live. The BJS berg jumper must be installed in the JPDF to provide the monitored ground reference for the
125 V dc. If there are multiple JPDFs connected to the dc mains, only one should have the Berg jumper installed. The dc
mains must be floated (isolated from ground) if they are connected to a 125 V dc supply (battery).
Note The IS220JPDF module must provide the single, monitored, ground reference point for the 125 V dc system.
Warning
The following steps should be completed to check the cabinet wiring and circuits.
➢ ➢ To check the power wiring
1. Ensure that all incoming power wiring agrees with the electrical drawings, supplied with the cabinet, and is complete and
correct.
Ensure that the incoming power wiring conforms to approved wiring practices as described previously.
2.
3. Ensure that all electrical terminal connections are tight.
4. Ensure that no wiring has been damaged or frayed during installation. Replace if necessary.
5. Check that incoming power (125 V dc, 115 V ac, 230 V ac) is the correct voltage and frequency, and is clean and free of
noise. Make sure the DACA converters, if used, are set to the correct voltage by selecting the JTX1 (115 V ac) or JTX2
(230 V ac) jumper positions on the top of the converter.
6. If the installation includes more than one JPDF on an interconnected 125 V dc system, the BJS jumper must be installed
in one and only one JPDF. This is because the parallel connection of more than one ground reference circuit will reduce
the impedance to the point where the 125 V dc no longer meets the not hazardous live requirement.
Verifying that the 125 V dc is properly grounded. A qualified person using appropriate safety procedures and equipment
should make tests. Measure the current from first the P125 V dc, and then the N125 V dc, using a 2000 Ω, 10 W resistor to
the protective conductor terminal of the Mark VIe control in series with a dc ammeter. The measured current should be 1.7 to
2.0 mA, (the tolerance will depend on the test resistor and the JPDF tolerances). If the measured current exceeds 2.0 mA, the
system must be cleared of the extra ground(s). A test current of about 65 mA, usually indicates one or more hard grounds on
the system, while currents in multiples of 1 mA usually indicate more than one BJS jumper is installed.
Note At this point the system is ready for initial application of power.
154 GEH-6721_Vol_I_BP
This equipment contains a potential hazard of electric shock or burn. Only personnel
who are adequately trained and thoroughly familiar with the equipment and the
instructions should install, operate, or maintain this equipment.
GEH-6721_Vol_I Mark VIe and Mark VIeS Control Systems Volume I
Public Information