Ground Integrity Check - GE CARESCAPE B850 Service Manual

8.2.4 Ground integrity check

Listed below are two alternative methods for checking the ground integrity:
continuity test"
whether the device's exposed metal and power inlet's ground connection has a power ground
fault condition.
Perform either test a) or test b) in accordance to your local regulations.
NOTE: Refer to the instructions delivered with the safety analyzer to perform each test.
a) Ground continuity test
The measuring device (MD) in the diagram below may be a digital multimeter or part of the
safety analyzer.
Acceptance criteria:
• For equipment without a power supply cord, the impedance between the protective
ground terminal and any accessible metal part which is protectively grounded shall not
exceed 0.1 ohms.
• For equipment with a power supply cord, the impedance between the protective ground
pin in the mains plug and any accessible metal part which is protectively grounded shall
not exceed 0.2 ohms.
b) Impedance of protective ground connection
This test is normally only required as a manufacturing production test to receive safety agency
compliance. Some country agencies do require this test after field equipment repairs (i.e.,
Germany's DIN VDE 0751 standards). Consult your country/local safety agency if in doubt.
Check compliance as follows:
1. A current of 25A from a current source with a frequency of 50 or 60 Hz with a no-load
voltage not exceeding 6 V is passed for at least 5 seconds, but not more than 10 seconds,
through the protective earth terminal or the protective earth pin in the mains plug and
each accessible metal part which could become live in case of failure in basic insulation.
2. The voltage drop between the parts described is measured and the impedance
determined from the current and voltage drop. It shall not exceed the values indicated.
and "b) Impedance of protective ground
Installation checkout
"a) Ground
connection". These tests determine
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