Elma DT5500
side 22
Test leads check
Set the range select switch to the 200
Ω
range. With the tip and alligator clip of the test
leads connected. The indicator should read 00.0
Ω
. When the leads are not connected the
display will read infinity indicated by “1”. This will ensure that test lead are under working
condition.
Insulation resistance measurements
a). Measurements at 200M
Ω
/250V
This is the voltage used for the majority of insulation resistance tests on normal installation
requirement. To measure insulation resistance, press the test button to power on the
tester. The LCD will displayed the insulation resistance. Section VII indicated that
subdivision of large installations might be necessary because of the large number of
parallel insulation resistance. In such a case, an installation may be divided into sections,
each being separately tested. Each section must have not less than fifty outlets, an outlet
being a switch, socket, lighting point etc. A switched socket counts as one outlet. The
minimum acceptable insulation resistance is 1M
Ω
. For a large installation, the capacitance
of the insulation will be high, and it will take longer for it to become charged by the direct
testing voltage. Care must be taken not to take a reading until there is a steady reading,
indicating that the charging process is complete.
Note:
The charge stored in the insulation will be discharged automatically when the test
button is released. Be careful not to turn the range switch knob whilst the test button is
pressed, or the instrument will be damaged.
b). Measurements at 2000M
Ω
/1000V
Some specifications require testing at 1000V. This voltage must also be selected where
the supply voltage of the installation is between 500V and 1000V. First, set the range
switch to 1000V and then proceed as indicated in a above for 500V testing. The above
note also applies to testing at 1000V. In addition the following applies.
Note:
Make sure that the circuit under does not include components Which will be
damaged by the 1000V applied. Many normal components of an installation are likely to be
damaged if tested at 1000V. Examples are power factor correction capacitors, low voltage
mineral insulated cables, electronic light dimmers, electronic ballasts and starters for
fluorescent lamps etc…
c). Lock power on Feature
For hands free operation a lock power on feature is incorporated on the press to test
button. Set LOCK button to lock test voltage, Pressing it again will tester off.
Low resistance (continuity) measurements
a). Set the range switch to 200
Ω
·))) Position
b). Connect the red test lead to the V
Ω
terminal and black to the COM terminal.
c). Connect the tips of the test leads to both ends of the circuit under test. read resistance
in
Ω
on the LCD.
d). When the impedance on circuit is below approximately
40
Ω
.It will indicate by a continuous beeper.
