GE ApexPro TT, Technical Manual

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7-8 ApexPro™ 2001989-351A
Checkout
Ground (earth) integrity
Listed below are two methods for checking the ground (earth) integrity, “Ground
Continuity Test” and “Impedance of Protective Earth Connection.” These tests
determine whether the device's exposed metal and power inlet's earth (ground)
connection has a power ground fault condition.
Perform the test method below that is required by your Country/Local governing
safety organization.
Ground continuity test
Completion of this test is checked by the following steps:
1. Disconnect the device under test from the power outlet.
2. Connect the negative (-) lead of the DMM to the protective earth terminal
(ground pin in power inlet connector) or the protective earth pin in the Mains
plug (ground pin in power cord). Refer to the US 120 VAC power cord figure
above.
3. Set the DMM to the milliohm ( mW ) range.
4. Connect the positive (+) lead of the DMM to all exposed metal surfaces on the
device under test. If the metal surfaces are anodized or painted, scrape off a small
area in a inconspicuous place for the probe to make contact with the metal.
5. Resistance must read:
„ 0.1 ohm or less without power cord
„
0.2 ohms or less with power cord
Impedance of protective earth connection
This test, unlike a ground continuity test, will also stress the ground system by using
special ground bond testers.
This test normally is only required as a manufacturing production test to receive
safety agency compliance (i.e., IEC 60601-1).
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 question.
Compliance is checked by the following steps:
1. A current not less than 10A and not exceeding 25A from a current source with a
frequency of 50 or 60 Hz with a no-load voltage not exceeding 6V is passed for
at least 5s 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.
Ground
Pin