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5. OPERATION
5.1.
CONNECTING LEADS
5.1.1.
On MΩ Range: Connect the red test lead into the VΩ terminal and the black terminal into the COM terminal.
5.1.2.
On 200Ω and ACV Range: Connect the red test lead into the "VΩ" terminal and the black lead into terminal "COM".
5.2.
TEST LEADS CHECK
5.2.1.
Set the range select switch to the 200Ω range. With the tip and alligator clip of the test leads connected, the indicator should read
00.0Ω. When the leads are not connected the display will read infinity indicated by "1". This will ensure that test lead are under
working condition.
5.3.
BATTERY CHECK AND REPLACEMENT
5.3.1.
If battery power is insufficient the LCD will display . 6 x 1.5V AA batteries are required.
5.3.2.
Remove the four screws which hold the battery cover to fit batteries.
5.4.
INSULATION RESISTANCE MEASUREMENT
5.4.1.
Measurements at 200mΩ/250V
5.4.2.
This is the voltage used for the majority of insulation resistance tests on normal installations.
5.4.2.1. To measure insulation resistance, press the test button to power on the tester. The LCD will display 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 1MΩ. 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.
5.4.3.
Measurements at 2000mΩ/1000V
5.4.3.1. 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 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.
5.5.
LOCK POWER ON FEATURE
5.5.3.1.
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 turn the tester off.
5.6.
LOW RESISTANCE (CONTINUITY MEASUREMENTS)
5.6.1.
Set the range switch to 200Ω position.
5.6.2.
Connect the red test lead to the V Ω terminal and black to the COM terminal.
5.6.3.
Connect the tips of the test leads to both ends of the circuit under test. Read resistance in Ω on the LCD.
5.6.4.
When the impedance on circuit is below approximately 40Ω. It will indicate by a continuous beeper.
5.7.
AC/DC VOLTAGE MEASUREMENTS
5.7.1.
Set the range switch to acV or dcV position.
5.7.2.
Connect red test lead to "V Ω" terminal and black test lead to terminal "COM".
5.7.3.
Connect test prods of test leads IN PARALLEL to the circuit being measured.
5.7.4.
Read the voltage value on LCD.
5.8.
POWER TOOLS AND SMALL APPLIANCES See (fig.1)
5.8.1.
This test would also apply to other similar equipment that has a power cable. For double insulated power tools, the megohmmeter
lead shown connected to the housing would be connected to some metal part of the tool (e.g chuck or blade).
NOTE: The switch of the device must be in the "ON" position and the mains power should be disconnected.
5.9.
AC MOTORS Refer to (fig.1)
5.9.1.
Disconnect the motor from the line by disconnecting
the wires at the motor terminals or by opening the
main switch. If the main switch is used and the
motor also has a starter then the starter must be held,
by some means, in the "ON" position. In the latter
case, the measured resistance will include the
resistance of the motor, wire and all other components
between the motor and the main switch. If a weakness
is indicated, the motor and other components should
be checked individually. If the motor is disconnected
at the motor terminals, connect one megohmmeter
lead to the grounded motor housing and the other
lead to one of the motor leads.
5.10.
DC MOTORS Refer to (fig.1)
5.10.1.
Disconnect the motor from the line. To test the brush
rigging, field coils and armature connect one
megohmmeter lead to the grounded motor housing and
the other lead to the brush on the commutator. If the
resistance measurement indicates a weakness, raise
the brushes off the commutator and separately test the
armature, field coils and brush rigging by connecting
one megohmmeter lead to each of them individually,
leaving the other connected to the grounded motor
housing. The above also applies to dc generators.
© Jack Sealey Limited
fig.1
Original Language Version
TA319.V2 Issue 1
11/3/21
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