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PORTABLE TEST SET
for HV AC Voltmeters
Model VMTS-.4
Nominal 400 Volt AC
voltage source for verification of HV voltmeter or other types of AC
voltmeters, requiring less than 500 microamps.
Battery operated solid
state, safe low power AC test source with built-in indicator light and
automatic switch for HV voltmeter test probe application.
Indicates either open or
shorted probe(s) or a faulty meter or an open ground lead by means of
combination of visible light and meter indication.
When using this tester,
connect the meter ground lead to the common screw at the bottom of the
tester and push the meter HV terminal into the hole at the top end.
The voltage indicator on
Ross Engineering Corporation Hi-Z® or Emergency Crew meters will vary
with different models. All of the meters with CAP TAP function and 200
or 250V range will normally have off-scale indication on the lowest
range(s). Higher Direct Line ranges will normally have readable values
on digital units, but may have very little deflection on some analog
units.
The meters are protected
from damage even on the lowest ranges and on the CAP TAP function as
long as the maximum voltage value engraved on the probe high voltage
contact end is not exceeded. Thus the meter may beset to give a good
indication with the tester.
The meter should be used to
test for voltage on the systems being checked with the same range
verified with the tester. If the meter has an over-range indication, a
higher range or direct line may be selected to read the actual voltage.
If there is a zero voltage reading on the higher range, that would
indicate a problem with that meter range, but the operator will know
that there is high voltage on the system. If no voltage is indicated
when checking the power system, recheck the meter with the tester to be
sure the meter is still operating properly.
If test set light does not
come on when test probe is applied, faulty operation is indicated in
either meter or test set. Test set can be checked by disconnecting
ground lead from test set common terminal. If light goes on when probe
terminal is depressed, test set is generating at least 60 volts, and
test probe resistance is below about 600,000 ohms or capacitance is over
about 800 picofarads. Voltage will drop proportionately with decrease in
load resistance (increase in load current), but will drop only very
little if load is pure (wattless) capacitance until over the 800
picofarad level. The supply will then rapidly saturate, reducing the
voltage to a very low value.
Caution:Test
sets are capable of several milliamps which can cause slight shocks.
Model VMT-.5 Voltmeter
Tester, Megmeter®
For portable hot stick
operation, this is a combination source of about 400V AC and about 500V
DC voltmeter tester-megohm leakage indicator in one small flashlight
size unit. Supplies 400V AC to Ross Engineering Corporation VM25-100
Series Hi-Z® meters with direct line and capacitance tap capability. The
500V DC megohm indicator will indicate contamination or leakage on the
capacitance tap or any insulation, even in the presence of an AC voltage
as high as 15kV AC with an ungrounded source. The common or ground lead
must be grounded to test for capacitance tap or direct line leakage to
ground. Unit will indicate in the range of from over 2,000 megohms down
to 20 megohms and less by means of a flashing neon lamp. Critical
leakage resistance values in capacitance taps and most HV insulation are
in the order of 20 megohms to over 2,000 megohms, and this unit is
designed for this range as well as short circuits.
Model VMT-.5-C HV Adapter
for Megmeter®
The
hot stick adapted VMT-.5-C is available as a combination 500V DC megohm
indicator 400V AC tester for voltmeters, capable of withstanding up to
15kV AC on capacitance taps or direct AC lines and reading DC leakage
resistance even on the energized capacitance tap or ungrounded high
voltage AC line.
Caution:
With 15kV isolation limiter test set output current is limited to approx
50 microamps at tip but is capable of several milliamps at 400V AC VM test
point which can cause slight shocks.
Caution:
Safety rules apply when using in the possible presence of high voltage.
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