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LT300 High current loop tester
User guide
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SAFETY WARNINGS
Safety Warnings and Precautions must be read and
understood before the instrument is used. They must be
observed during use.
The earth loop impedance test creates a temporary low resistance
path between live and earth for the duration of the test. This is
particularly hazardous with both an instrument and an installation
fault.
Working practices and hazard avoidance must take care of this
risk
Continuity of protective conductors and earthed equipotential
bonding of new or modified installations must be verified before
carrying out an earth fault loop impedance tests.
Circuit connections and exposed metalwork of an installation or
equipment under test must not be touched in case of the
presence of hazardous touch voltages
Do not leave the instrument connected to the mains supply when
not in use.
Ensure that hands remain behind guards of probes/clips when
testing.
The instrument should not be used if any part of it is damaged.
Test leads, probes and crocodile clips must be in good order,
clean and with no broken or cracked insulation.
The battery cover must be in place whilst conducting tests.
Some national safety authorities recommend fused leads for
voltage measurement on high energy systems. If RCD or Loop
tests are made it may cause the fuse to rupture, and so they must
be used with caution on voltage testing.
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Summary of Contents for Megger LT300
- Page 1 LT300 High current loop tester User guide SAFETY WARNINGS Safety Warnings and Precautions must be read and understood before the instrument is used. They must be observed during use. The earth loop impedance test creates a temporary low resistance path between live and earth for the duration of the test. This is particularly hazardous with both an instrument and an installation fault.
- Page 2 NOTE THE INSTRUMENT MUST ONLY BE USED BY SUITABLY TRAINED AND COMPETENT PERSONS. Users of this equipment and/or their employers are reminded that Health and Safety Legislation requires them to carry out valid risk assessments of all electrical work so as to identify potential sources of electrical danger and risk of electrical injury such as inadvertent short circuits Symbols used on the instrument:...
- Page 3 3 lead plugs because of the danger of electrocution. These leads should only be used by a competent person. Supply Category rating: The LT300 is designed for use on 300 V CAT IV Phase to Earth and...
- Page 4 550 V Phase to Phase applications (400 V @ 16 Hz). Loop Testing Select either the 20 Ω or 200 Ω measurement range depending on: 1. The required measurement resolution 0.01 Ω (20 Ω range) or 0.1 Ω (200 Ω range). 2.
- Page 5 instrument and the GREEN (EARTH) lead to the GREEN/BLUE socket (alternatively use the mains plug test lead RED and BLUE connections). 2. Connect the RED lead to Phase and the GREEN lead to Neutral (or connect the mains plug to the wall socket). 3.
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Page 6: Specification
Frequency indicators The frequency indicator shows the system frequency the circuit is using. It is intended as a guide only. For accurate frequency measurement a suitable test instrument should be used. Nominal frequency bands are: 50/60 Hz 400 Hz 16 Hz 15 Hz to 18 Hz 40 Hz to 70 Hz 260 Hz to 490 Hz... - Page 7 Voltage measurement 0 V to 550 V (400 V @ 16 Hz) Range: ±5% ±2 V Accuracy: 16 Hz to 400 Hz Range: Loop Impedance measurement Phase to Earth 50 V to 300 V (400 V @ 16 Hz) Supply: Loop impedance measurement Phase to Phase 50 V to 550 V (400 V @ 16 Hz) Supply:...
- Page 8 T +1 416 298 6770 F +1 416 298 0848 E casales@megger.com Megger products are distributed in 146 countries worldwide. This instrument is manufactured in the United Kingdom. The company reserves the right to change the specification or design without prior notice.