Ampcontrol Pty Ltd
– ABN 28 000 915 542
IPM V2 USER MANUAL
IPM2B003 Revision 15
– MAY/18
Uncontrolled Copy - Refer to Ampcontrol Website for Latest Version
Page 30 of 83
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6
EARTH PROTECTION FUNCTIONS
The IPM relay provides the following earth protection functions:
Earth Leakage
Insulation Test
Earth Continuity
6.1 Earth Leakage
6.1.1 Introduction
Protection systems are defined in AS/NZS 2081 for use in fault limited systems. This standard
describes the requirements of Earth Leakage protection to initiate a trip of the circuit interrupting device
when a selected value of earth fault current is exceeded for a certain amount of time.
All protection systems must comply with this standard as stated in AS/NZS 4871, which sets out the
general requirements for the design, construction and testing of electrical equipment directly associated
with mining and quarrying activities. Part of these requirements includes designing for electrical faults,
and the standard outlines the safe touch potential which must be considered in electrical protection
design. Acceptable touch potential levels are described using a series of curves as shown in Figure
6.1.
Figure 6.1:
AS/NZS 4871 Safe Touch Potential Levels (Figure C1 from the standard)
The IPM V2 relay
‟s earth leakage protection function has been designed in accordance with AS/NZS
3190
– Approval and Test Specification – Residual Current Devices (current-operated earth-leakage
devices). Given this, it is important to consider the performance of the earth leakage protection provided
by the IPM V2 and
assess how the relay‟s performance compares with the requirements of AS/NZS
2081.
Testing was completed to assess the ability of the IPM V2 relay to trip within acceptable levels.
The results for the earth leakage tripping times of the relay are detailed in APPENDIX 1: IPM Earth
Leakage Tripping Curves. These results show that the tripping times are well within those specified by
the relevant standards. The tripping times reduce for higher fault currents, improving the performance of
