MS5908 TRMS voltage GFCI RCD Tester Circuit Analyzer

Measurement

Ranges

Resolution

Accuracy

Line Voltage

85.0~265.0V

0.1V

±(1.0%+0.2V)

Neutral-Ground V

0.0~10.0V

0.1V

±(2.5%+0.2V)

Peak Line Voltage

121.0~374.0V

0.1V

±(1.0%+0.2V)

Frequency

45.0~65.0Hz

0.1Hz

±(1.0%+0.2Hz)

% Voltage Drop

0.1%~99.9%

0.1%

±(2.5%+0.2%)

Voltage Loaded

10.0~265.0V

0.1V

±(2.5%+0.2V)

Impedance –Hot

0.00~3.00Ω

0.01Ω

±(2.5%+0.02Ω)

Neutral & Ground

>3.00Ω

Unspecified

RCD Trip Time

1ms~6.500s

1ms

±(1.0%+2ms)

RCD Trip Current

30mA

0.1mA

±(1.0%+0.2mA)

GFCI Trip timer

1ms~6.500s

1ms

±(1.0%+2ms)

GFCI Trip Current

6mA

0.1mA

±(1.0%+0.2mA)

Measurement Item

Normal measurement result

Fault measurement result

Possible cause

Trouble shooting

Phase voltage

108-132V

(120V)

198-242V

(220V)

The voltage is too high or too low.

The circuit is overloaded.

Redistribute the circuit load.

High impedance points are found in switchboard or circuit.

Locate the high impedance and repair or replace relevant parts.

The supply voltage is too high or too low.

Consult the power supply department

Voltage to earth of zero line

<2V

>2V

Leakage current 

Find the current source: Is there any multipoint ground? Does the equipment or device leak current?

Three-phase imbalance

Check and redistribute the load

Harmonic interference

Increase neutral line conductor, install electrical filter or use other methods to reduce the harmonic interference. 

Peak voltage

153-185V

(120V) 280-342V

(220V)

The voltage is too high or too low.

The supply voltage is too high or too low.

Consult the power supply department.

The electron device in the circuit results in the electric wave distortion.

Revaluate and relocate (if necessary) the electronic device in the circuit

Frequency

60Hz

(50Hz)

The frequency is too high or too low.

The supply frequency is too high or too low.

Consult the electricity department

Measurement Item

Normal measurement result

Fault measurement result

Possible cause

Trouble shooting

Voltage drop

<5%

The voltage drop is too high.

The circuit is overloaded.

Redistribute the circuit load

Compared with power transmission length, the wire is small.

Rearrange the wire in compliance with the relevant standard.

High impedance point exists between the circuit and switchboard.

Repair or replace the parts generating high impedance

Measurement Item

Normal measurement result

Fault measurement result

Possible cause

Trouble shooting

Conductor impedance for live line and zero line

No. 14 line (2.0mm²)

<0.15Ω/m

The impedance is too high

The circuit is overloaded.

Redistribute the circuit load.

No. 12 line  (3.3mm²)

<0.1Ω/m

The wire diameter is too small for the power transmission length.

Check the wire diameter and rearrange the wire accordingly.

No. 10 line (5.2mm²)

<0.03Ω/m

High impedance point exists in the circuit or switchboard.

Locate the high impedance and repair or replace the parts

Conductor impedance for earth line

For personnel safety

<1Ω

The impedance is too high

The wire diameter is too small for the power transmission length.

Check the wire diameterand rearrange the wire accordingly.

For equipment safety

<0.25Ω

High impedance point exists in the circuit or switchboard.

Locate the high impedance and repair or replace the parts

Measurement Item

Normal measurement result

Fault measurement result

Possible cause

Trouble shooting

RCD test

 RCD is triggered within the specified time.

Fail to be triggered within the specified time.

 The RCD is installed improperly.

Check the circuit and install the RCD according to the manufacture requirement and relevant standard.

Fail to be triggered (Invalid test)

RCD goes wrong.

Repair or replace RCD.

Measurement Item

Normal measurement result

Fault measurement result

Possible cause

Trouble shooting

GFCI

 test

 GFCI is triggered within the specified time.

Fail to be triggered within the specified time.

 The GFCI is installed improperly.

Check the circuit and install the GFCI according to the manufacture requirement and relevant standard.

Fail to be triggered (Invalid test)

GFCI goes wrong.

Repair or replace GFCI.