for High Voltage DC, AC or DC+AC Voltmeters



Caution: A capacitive load can retain a lethal charge.

Nominal 1,000 Volt DC or 400V AC voltage source for verification of a HV DC, AC or DC+AC voltmeter, or other types of DC voltmeters requiring less than 500 microamps. Tester can indicate 0 to 15kV depending on type of meter.

9V Battery operated solid state, low power DC test source with built-in indicator light and automatic switch for HV voltmeter test probe application.

Indicates either open or shorted probe(s), 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 negative terminal common screw at the bottom of the tester and push the meter positive HV terminal into the hole at the top end to turn on the tester.

The voltage indicator on Ross Engineering Corporation DC, AC or DC+AC 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 units, particularly DC on AC only or AC on DC only unit.

The meters are protected from damage even on the lowest ranges and on the CAP TAP function as long as the maximum voltage value indicated on the probe high voltage contact end is not exceeded.

The meter should be used to test for voltage on the system 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 any 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 proper tester to be sure the meter is still operating properly, or is an AC only or DC only meter.

If tester set light does not come on when HV meter probe tip is applied, faulty operation is indicated in either meter or test set. Test set can be checked by disconnecting meter ground lead from tester common terminal. If light goes on when probe terminal is depressed, test set is generating at least 60 volts, and meter probe resistance is above about 600,000 ohms. If load capacitance is very high it may take a very long time for DC to charge to maximum indication. Very high capacitance such as a long shielded cable may act like a shorted cable with AC tester and light will not indicate.

Voltage will drop proportionately with decrease in load resistance (increase in load current), but will drop only very little if load is very high resistance or capacitance until over the 800 picofarad level. The DC tester will then reduce the voltage to a very low value until the capacitance is fully charged, allowing the meter then indicating the proper voltage.

Caution: Pocket Testers are capable of up to several milliamps which can cause appreciable shocks especially with charged capacitance. Never touch capacitive load unless shorted (the load may retain a lethal charge). To avoid shock be sure the load is discharged before and after testing. To prevent explosive arcing if safety ground is applied to HV power source side, be sure that high current is not available.

Model VMT-.5 Voltmeter Tester, Megmeter®



For portable hotstick 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 Corp. 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 variable 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 hotstick adapted VMT-.5 is available as a combination 500V DC megohm indicator and 400V AC tester for voltmeters, capable of indicating DC resistance of high voltage probes or other items rated for at least 500V DC.

Caution: With 15kV isolation limiter, test set output current is limited to approximately 50 microamps at tip. Without the 15kV isolation limiter, the DC current limit is several milliamps. The AC source is capable of several milliamps at 400V AC voltmeter test point, either of which can cause slight shocks.

Caution: Safety rules apply when using in the possible presence of high voltage.

Detailed Information

Portable Test Set

Voltage Sensing

Hi-Z® Capacitance

Specifications are for reference only and are subject to change.
Contact Ross Engineering Corp. for current information.