Voltmeters Selection Guide
A voltmeter is an instrument that shows the voltage between two points in volts; for panel-mount models, the number of phases, range, supply and size decide the selection.
What is a voltmeter? A voltmeter is an instrument that shows the electrical voltage between two points of a circuit in volts (V). A panel-mount voltmeter is mounted permanently so that this value can be monitored continuously from the enclosure door; in mains, generator and regulator panels it shows whether the voltage is within the expected range. It displays the voltage and does not open the circuit by itself.
This guide explains what to look at when choosing products in the Voltmeters category.
Types of voltmeters
The listed models are in the digital voltmeters subcategory and are separated by the voltage they measure.
- Single-phase AC voltmeters: Shows a single voltage. In the product data of Tense single-phase AC models such as the DJ-V96 and of the GEMO DPM models, the upper value of the measuring range is stated as 500 V AC.
- Three-phase voltmeters: Shows the voltages of the three phases in a single housing. The product data of the Tense DJ-V72S, DJ-V96S and DJ-V96T models states that phase-neutral and phase-phase voltages are displayed, and for the DJ-V96T also phase sequence information.
- DC voltmeters: For direct voltage sources such as battery banks and DC busbars; the product data of the Tense DC models states that reverse polarity is indicated.
- DIN rail voltmeter: The Tense DV-DIN is mounted not on the enclosure door but on the rail inside the enclosure.
- Regulator voltmeters: The Tense models with the RG code are for regulator panels. According to the product data, it shows the input and output voltage of the regulator together; depending on the model it includes high-low voltage protection, a servo motor control output and an audible alarm. The related devices are in the servo regulators category.
What to look at when choosing a voltmeter
- Voltage type and measuring range. AC and DC models are separate. In a three-phase mains, the phase-phase voltage is √3 times the phase-neutral voltage (400 V for 230 V phase-neutral). If phase-phase voltage is to be measured, the measuring range must cover this value; in the product data of the regulator models the upper value is 300 V AC.
- Number of phases. If only one voltage is to be monitored, a single-phase model is chosen; if the three phases are to be monitored together, a three-phase model is chosen.
- Supply. Supply values such as 110-230 V AC, 230 V AC and 24-250 V AC/DC appear in the product names; compare this value with the auxiliary voltage in the enclosure.
- Housing and display. Housings of 36 × 72, 48 × 48, 48 × 96, 72 × 72 and 96 × 96 mm are listed; the panel cut-out dimensions are taken from the product manual. The digit height is 9 mm, 14 mm and 20 mm in the product data; in enclosures that will be read from a distance, a model with large digits makes reading easier.
The conductor cross-section of the measuring leads and their fuse protection are determined according to the project and the manufacturer's data.
Choosing between a voltmeter and similar devices
- A panel voltmeter is an indicating device. If the load has to be disconnected when the voltage goes outside the limits, voltage protection relays with contact output are selected according to the project.
- If a large cut-out cannot be made in the door, or a separate indicator is wanted for each phase, voltmeter pilot lights that fit a 22 mm hole can be used.
- If current, power or energy is also to be read besides voltage, panel-mount multimeters and power network analyzers are in separate categories.
- If only frequency is to be monitored, frequency meters are listed separately.
- For temporary measurements during troubleshooting and commissioning, handheld digital multimeters are used.
Brands in this category
- Tense: AC and DC panel voltmeters with the DJ-V code, the DIN rail model with the DV-DIN code and regulator voltmeters with the RG code.
- Entes: EVM series single-phase and three-phase digital voltmeters; 48 × 96, 72 × 72 and 96 × 96 mm housings.
- GEMO: panel-type digital AC voltmeters with the DPM48 and DPM72 codes.
- Schneider Electric: voltmeters with LED display and single-phase or three-phase measuring capability.
Order notes
- Voltmeters are sold per piece; for those listed as made to order, the lead time is confirmed before the order.
- Most Tense RG models appear in the product name only as digital voltmeters; to monitor mains or busbar voltage, look at the models with the DJ-V, EVM and DPM codes.
- In the search you can use the manufacturer code in the product name (for example DJ-V96, EVM-3S-72, DPM72-VAC500).
Comparison and selection table
| Selection Criterion | Analog Moving-Iron Voltmeter | Single-Phase / Ø22 mm Digital Voltmeter | Three-Phase (3P) Digital Panel Voltmeter |
|---|---|---|---|
| Voltage Range | 0–300 V AC or 0–500 V AC pointer scale | 20–500 V AC (or DC 0–100 V / 0–600 V) | Measures both Phase-to-Phase (400 V) and Phase-to-Neutral (230 V) |
| Panel Cutout | 72×72 mm or 96×96 mm (paired with external selector switch) | 48×48, 72×72, 96×96 mm, DIN rail or Ø22 mm pilot-light style | 72×72 mm or 96×96 mm (pushbutton scroll or 3-row LED display) |
| Key Advantage | Self-powered needle indication, instant visual check | Crisp digital readout, optional high/low voltage alarm relay | Eliminates separate rotary voltmeter selector switch on panel door |
| Typical Application | Traditional switchboards, generators & voltage stabilizers | Compact machine panels, Ø22 mm door voltage indicators | Main low-voltage switchboards, PFC & motor control centers |
Frequently asked questions
What is the difference between phase-neutral and phase-phase voltage?
Phase-neutral voltage is measured between a phase conductor and neutral, and phase-phase voltage between two phase conductors. In a three-phase system the phase-phase voltage is √3 times the phase-neutral voltage; in a mains with 230 V phase-neutral voltage the phase-phase voltage is 400 V. If phase-phase measurement is to be made, the measuring range of the voltmeter must cover this value. The product data of the Tense DJ-V72S, DJ-V96S and DJ-V96T models in this category states that both voltage groups are displayed.
Can DC voltage be measured with an AC voltmeter?
A voltmeter is selected for the voltage type stated in the product data: a model whose measuring range is given as VAC is for alternating voltage and a model given as VDC is for direct voltage. For direct voltage sources such as battery banks or DC busbars, a DC voltmeter is selected. The product data of the Tense DC models in this category states that reverse polarity is indicated; when the leads are connected the wrong way round, the device shows this on the display.
How many voltmeters are needed in a three-phase enclosure?
Since a three-phase voltmeter shows the voltage of the three phases in a single housing, one device is enough. If single-phase voltmeters are used, either a separate device is fitted for each phase or a single device is switched manually between the phases with a voltmeter selector switch. With a selector switch solution the voltages are not seen at the same time; an outage on one phase is noticed only when the relevant position is selected.
How does a regulator voltmeter differ from a normal panel voltmeter?
The Tense models with the RG code are control and indicating units whose area of use appears as regulators in the product data. They show the input and output voltage at the same time; depending on the model there are voltage protection, a servo motor control output, an audible alarm and a regulator output set. For simply monitoring mains or busbar voltage, general-purpose models such as the panel voltmeters with the DJ-V code and the Entes EVM series are suitable.
Does a panel voltmeter provide voltage protection?
A general-purpose panel voltmeter is only an indicating device; it does not cut the circuit when the voltage goes outside the limits. To disconnect the load on overvoltage and undervoltage, a voltage protection relay with contact output is used. The audible alarm on some models does not replace a protection relay; the protection functions on the Tense RG models are for the regulator. The protection required is determined by the project of the installation.