Megger LRCD200 series, Руководство пользователя

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Bonded Metalwork Testing
Repeat the above test but with the Green lead connected to the exposed
metalwork.
For a Hi Current Phase to Earth loop impedance measurement at a power
socket, repeat the above test using the Mains plug test lead supplied.
Phase-Neutral or Phase-Phase loop impedance
1. Connect the 3-wire test lead to the instrument.
2. Connect the RED [L1] lead to PHASE. Connect the GREEN [L0] lead and
the BLACK lead (Black lead - ensure the black lead is connected to the
green lead) to NEUTRAL (or the 2nd PHASE for Phase to Phase loop
measurement on the LRCD220).
3. The supply voltage is displayed.
4. Press the [TEST] button to start a loop test.
5. After a short delay the measured loop value is displayed. If desired the
test can be repeated by pressing the [TEST] button again.
N No o tt e e:: Phase – Phase (415 V) loop test is only possible on the LRCD220.
Prospective Fault Current display [PFC]
1. On completion of a test, press the [PFC] key.
2. The prospective fault current is displayed in Amps or kA.
Notes:
The prospective short circuit current (PSCC) of a circuit is the largest
Prospective Fault Current (PFC). In a single phase system, this would be
the larger of the earth loop PFC and the neutral loop PFC. In a multi-phase
system phase-phase loops also need to be considered and these can be
measured using the (Hi) switch position.
The PFC is calculated by using the sum:-
Nominal supply voltage
Loop resistance
The supply voltage used in the calculation depends on the measured
voltage. The instrument uses the following voltage values:-
Actual measured Nominal voltage
voltage
>80 V and <150 V 110 V (LRCD220 only)
>150 V and <300 V 230 V
>300 V 400 V (LRCD220 only)
PFC measurement accuracy
An accurate PFC measurement requires an accurate measurement of the
loop resistance. The difference of a few digits in the loop resistance
measured will have a large effect on the PFC displayed.
Warning messages
Noise Indication
The symbol is displayed when excessive noise caused by other
equipment exists on the circuit under test. This noise can affect the
accuracy of the loop measurement.
The operator is advised to repeat the measurement or, if the noise symbol
continually appears, investigate the cause.
Voltages greater than 280V [>480V on LRCD220]
LRCD200/210: If a voltage greater than 280 V is detected, the
display will show >280 V.
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PFC=