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CERAMIC FUSE. It is essential that any
replacement fuses fitted to the instrument
conform to this specification. GLASS FUSES
MUST NOT BE USED due to their low
rupturing capacity. Failure to observe this
may result in injury to the operator, damage
to the instrument, or both.
GENERAL PRECAUTIONARY NOTES
The instrument circuit incorporates a 10 A fuse in
series with the 'COMMON' terminal, to give the
user additional protection should the instrument
be connected across a high energy source when
its range switches are set wrongly. It is most
important that the integrity of this fuse is checked
(by a continuity test with the leads connected
together) before and after any measurement is
made.
A check before measurement ensures that a
circuit under test does not appear falsely to be
"dead". A check after measurement ensures that
the reading is valid and that the fuse did not
rupture while the measurement was being made.
Establishing that a circuit is de-energized before
making connection for current and resistance may
be achieved by (i) checking that the appropriate
switches are off and (ii) testing, with the
instrument set to a voltage range, to see that there
is no potential present.
When measuring current or voltage, ensure that
the instrument is set to either "AC ~" or "DC . . ."
as appropriate, and switch to a suitable range
before making connections to the circuit under
test. When in doubt always switch to the highest
range and work downwards, there is no necessity
to disconnect the leads as the switch position is
changed. Do not, however, switch off by turning
to a blank position.
The instrument is flash tested at 7 kV a.c., but if it
is used, with accessories, on circuits operating at
voltages in excess of 1 kV, it should be kept at
the low potential end of the circuit, (near earth
potential), or other suitable safe-guards must be
applied.
The instrument is intended for use horizontally.
The meter pointer should rest over the zero
position on the top scale, when there is nothing
connected to the terminals. If it does not
adjustment may be made using the slotted screw
head on the front panel.
NON SINUSOIDAL WAVEFORMS
In as much as rectifier moving coil instruments
give readings on a.c. proportional to the mean
and not the r.m.s. value of the waveform with
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