Mastech MS5908C User manual

MS5908C
Circuit Analyzer
User’s Manual
Ω
TEST
mA
VA
ms
Hz%
VA
ms
%
AC
L - N
L - E
N - E
Peak
Z - L
Z - N
Z - E
ASCC
5 A 8 A 10 A HOLD
NEL
V Vd Z RCD GFCI
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[]
MS5908C

01 02
General Instructions
This circuit analyzer is a special test device
designed for AC low-voltage distribution line quick
fault location. With simple operation, accurate
measurement and other features, it can detect
multiple problems on a line, such as causing to
electric shock, electrical fire, abnormal operation
of equipment, etc.
Functions:
• TRMS measuring AC voltage
• Artificial load 5A, 8A, 10A measuring line drop
• Measuring phase voltage, neutral line (zero line)
voltage to earth, peak voltage, frequency
• Measuring phase (live line), neutral line (zero line),
earth line conductor impedance
• Identifying 3-wire socket connection mode (zero
for left and live for right, having earth line or not)
• Test the reliability of residual current device (RCD)
and response action time
• Test the reliability of GFCI action and response
action time
• Backlight function and data hold function
Warning
Do not use this instrument without reading,
understanding and following the instructions
in this manual. Read and follow them carefully,
as well as all warnings and instructions marked
on the instrument!
To prevent damages to the instrument, it should
not be used for measuring the output of UPS
equipment, nor for measuring adjustable light
and square wave generator!
For measurement accurency during repeated
usage, allow at least 30 seconds between two
consecutive measurements to facilitate
equipment cooling when measuring voltage
drop and cable impedance.
To ensure accurate measurement data, please
check whether there is important load or heavy
load in the line before testing. Turn off the heavy
load, if necessary, then retest.

05 06
L - N N - E Peak
Voltage (V ): real time display of cable connection
status and display the voltage drop of current load
and measurement results of phase voltage drop
TRMS. This test item includes 3 submenus, namely
load with 5A, 8A and 10A. Press Up “ ”or Down
“ ” selection key on the sub test item to enter the
relevant test item.
One analog load can be added to live line (phase
line) and zero line (neutral line) for the analyser
to measure the voltage drop, and then calculate the
voltage drop of 5A, 8A and 10A load separately.
Under the appropriate test function, press the test
key “ ” to test.
d
Menu Operation
The main test items of the analyser are located on
the bottom of display, including five test items,
namely: voltage (V), voltage drop (Vd),
impedance (Z), RCD and GFCI. Press the main test
item selection key “ ” to select relevant test item.
V Vd Z RCD GFCI
Voltage (V): real time display of TRMS of phase
voltage, wiring status and frequency. This test item
includes 3 submenus, namely phase voltage (L_N)
TRMS, voltage to earth of neutral line (zero line)
(N_E) TRMS, peak voltage (Peak). Press Up “ ”
or Down“ ” selection key on the sub test item to
enter the relevant test item.
Press “FUNC”Press “FUNC” Press “FUNC”
Press “FUNC”
Press “FUNC”
Press“ ”
Press“ ” Press“ ”
Press“ ” Press“ ”
Press“ ”

11 12
Wiring test
NEL
The wiring test result will be shown immediately
after the analyzer is plugged to the socket under
test. The analyzer can identify the following wiring
conditions and display the test result on the screen.
Wiring
condition
Normal
No ground
wire is found
The live/zero
line is
connected
inversely.
Other
conditions
Screen display
L E N Caption
Off
On
Flashing
Where any wiring abnormality is found, the
analyzer can only complete partial measurement.
Where there is no earth line, the analyzer can only
measure the phase voltage and voltage drop.
Notes: The analyzer can't detect
1. Circuit voltage, i.e. the voltage between two live
lines;
2. Combined fault;
3. Reverse connection of earth line and neutral line.
Voltage measurement
The normal measured value of phase voltage is
220V±10%, 50Hz. The peak voltage of sine-wave
alternating current is 1.414 times to the effective
value of phase voltage. The voltage to earth of
neutral line shall be less than 2V. In the single-phase
circuit, if the “voltage to earth of zero line” is high,
it indicates that the leakage current in zero line or
earth line is high. In the three-phase circuit with
neutral line, a high “voltage to earth of zero line”
indicates that the three-phase load is imbalanced
or the neutral line is affected by harmonic
interference. Excessive voltage (voltage to earth
of zero line) will result in running deviation or
interruption.

15 16
Voltage drop (V ) measurement
Dummy load shall be used in the circuit to
measure the load phase voltage and then calculate
the voltage drop. The voltage drop and load phase
voltage will be displayed when the load reaches
5A, 8A and 10A.
In terms of qualified circuit, when measurement
is made in the most remote socket from the
switchboard, the voltage drop shall be less than 5%.
During the measurement of the remaining sockets
of the same area, the farthest socket from the
switchboard shall be measured first and then other
measurements shall be made from the distant to
the near. The reading of the voltage drop shall be
shown on the downward trend.
If the voltage drop exceeds 5% and no obvious
drop of reading is found during the measurement
made near the switchboard, it indicates that the
first connection point goes wrong. In this case,
perform a visual inspection of the wire connection
among the first connection point, equipment and
switchboard and the connection of breaker
(air-break switch). Usually, a high impedance point
generates heat. To locate this problem, infrared
radiation thermometer can be used. In addition, we
can directly measure the voltage on both sides of
the breaker (air-break switch) to locate the point of
failure.
d If the voltage drop exceeds 5%, and during the
measurement made near the switchboard, the
reading drops constantly and no obvious change
is found between the two sockets, it indicates that
the lead wire diameter is too small compared with
the transmission distance, the transmission
distance is too long or the circuit is overloaded.
Under such circumstances, check the cable to see
if the lead wire diameter complies with the required
standard, and measure the lead wire current to see
if it is overloaded.
If the voltage drop exceeds 5% and there is an
obvious change of voltage drop reading between
the two sockets, it indicates that a high impedance
point exists between the two sockets. Usually,
problems are found at the contact, such as poor
connection, loose connector, or socket problem.

19 20
Fault localization and trouble shooting
Measurement
Item
Normal
measurement
result
Fault
measurement
result
Possible
cause
Trouble
shooting
Conductor
impedance
for
live line
and
zero line
The
impedance
is
too high
Redistribute
the
circuit load.
The circuit
is overloaded.
Check the
wire diameter
and
rearrange
the wire
accordingly.
High
impedance
point exists in
the circuit
or
switchboard.
Locate the
high
impedance
and repair
or replace
the parts
The wire
diameter is
too small
for the power
transmission
length.
Check
the wire
diameter and
rearrange
the wire
accordingly.
Locate
the high
impedance
and repair
or replace
the parts
The wire
diameter is
too small
for the power
transmission
length.
High
impedance
point exists
in the circuit
or
switchboard.
The
impedance
is
too high
Conductor
impedance
for
earth line
For
personnel
safety
<1Ω
For
equipment
safety
<0.25Ω
No. 14 line
(2.0mm )
<0.15Ω/m
No. 12 line
(3.3mm )
<0.1Ω/m
No. 10 line
(5.2mm )
<0.03Ω/m
Residual current device (RCD) test
During the RCD test, the analyzer will generate a
low current between live line and earth line by
means of a fixed resistance, which will affect the
current balance between live line and zero line.
According to UL, this current trigger shall be less
than 30mA. The RCD shall response to the current
imbalance by cutting off the power. The analyzer
will display the value of the current triggered (mA)
and response time (ms).
The word “TEST” will be displayed when the button
“ ” is pressed, which means the test is in the
process. RCD shall be triggered within the specified
index to cut off the power of the circuit under test.
If the RCD fails to be triggered, the analyzer will
stop testing automatically after 6.5 seconds.
Analysis on RCD shall be made according to the
test result to see if it goes wrong, is installed
properly or protects the circuit effectively.
Notes:
1. Check the circuit to see if there is heavy load over
the circuit before testing and, if necessary, turn
off the load to avoid wrong test result.
2. Earth connection is required when the RCD is
tested in the 2-wire system (without earth line). .
2
2
2

25 00-05-2999
1) The analyzer is powered by six AAA batteries.
2) Cut off the power and pull out the test line.
3) Unscrew the battery compartment and open the cover.
4) Replace the batteries.
5) Ensure the batteries are installed properly
(Do not mismatch polarity)
6) Put back the cover and tighten the screws.
Maintenance
Battery installation and replacement:
Cleaning:
Use soft cloth and neutral cleanser to clean the housing.
Use of abrasive or organic solvent is not allowed.