Voltmeter Symbol
Definition: The Voltmeter symbol represents a voltage-measuring instrument in circuit diagrams, depicted as a circle enclosing the letter 'V', connected in parallel across the two nodes whose potential difference is to be measured, as defined by IEC 60617-08 (measuring instruments) and ANSI Y32.2 / IEEE 315-1975; the designator is V or VM.
Also known as: voltmeter, voltage meter, VM symbol, V meter, electrovoltmeter, panel voltmeter, digital voltmeter, DVM.
What the Voltmeter symbol means
The Voltmeter symbol denotes a measuring instrument that quantifies the electric potential difference, expressed in volts (V), between two points in a circuit. The circle-with-V convention is drawn connected in parallel (shunt) across the component or branch being measured, reflecting the instrument's extremely high input impedance — typically 1 MΩ to 10 MΩ for analog meters and greater than 10 MΩ for digital multimeters — which ensures negligible current draw and minimal loading of the circuit.
In a schematic, the Voltmeter symbol communicates both a measurement intent and a circuit connection requirement: the two terminals of the voltmeter symbol must connect to different nodes at the same level of the circuit hierarchy. Engineers and technicians reading the diagram understand that the voltmeter is non-intrusive at audio and power-supply frequencies but that its input capacitance and finite impedance must be considered in high-frequency or high-impedance circuits.
How to identify the Voltmeter symbol
The Voltmeter symbol is a circle of uniform diameter with the uppercase letter 'V' centred inside. Two connection terminals — one positive (+) and one negative (−) — exit from the circle, typically from the top and bottom or from the left and right sides. The circle-with-letter convention distinguishes meters from other round symbols: 'A' inside denotes an ammeter, 'W' a wattmeter, 'Ω' an ohmmeter. In some legacy British and IEC drawings, the voltmeter may appear as a rectangle with 'V', but the circle form is universal in modern IEC 60617-08 and ANSI Y32.2 practice.
Function in a circuit
The Voltmeter measures the voltage (electric potential difference) across two nodes in a circuit without significantly altering the circuit's operating conditions, by virtue of its high internal impedance. When connected in parallel across a resistor, battery, or power supply terminal, it provides a numerical voltage reading in volts (V), millivolts (mV), or kilovolts (kV) depending on the selected range, enabling fault-finding, performance verification, and calibration tasks.
Standards: IEC vs ANSI
| IEC 60617 | IEC 60617-08 defines the voltmeter symbol as a circle enclosing the letter 'V', used to represent any voltage-measuring instrument regardless of its operating principle (moving-coil, digital, electrostatic). The standard specifies the symbol for use on single-line and elementary circuit diagrams. |
|---|---|
| ANSI/IEEE 315 | ANSI Y32.2-1975 (reaffirmed 1989) / IEEE 315-1975 defines the voltmeter symbol identically: a circle with the letter 'V' inside, connected in shunt. The designator VM or V is used on the schematic adjacent to the symbol. |
| Key difference | Identical in both IEC 60617-08 and ANSI Y32.2/IEEE 315 — both standards specify a circle enclosing 'V'. Older British Standard BS 3939 used the same convention. Regional difference is negligible for this symbol. |
Terminals / pins
| Pin | Name |
|---|---|
| pos | + |
| neg | - |
Typical values
Measurement range: millivolts (mV) to kilovolts (kV); typical analog panel meter full-scale: 1 V, 10 V, 30 V, 100 V, 300 V, 600 V; digital multimeter AC/DC range: 200 mV to 1000 V; input impedance: 1 MΩ (analog) to >10 MΩ (digital); accuracy: 0.1–3% (analog), 0.01–0.5% (digital).
Where the Voltmeter symbol is used
- Power distribution panel schematics showing permanent panel-mount voltmeters monitoring bus voltage
- Battery charger and UPS circuit diagrams indicating measurement points for output voltage verification
- Motor control centre (MCC) one-line diagrams displaying voltage measurement on feeder buses
- Laboratory bench power supply schematics with voltmeters across the output terminals
- Automotive wiring diagrams showing voltmeter connections across battery and alternator output
- Test-procedure call-outs in electronic equipment service manuals marking where to probe with a DMM
- Renewable energy system diagrams (solar, wind) showing DC bus and inverter output voltage monitoring
Example
In a DC power supply schematic, the Voltmeter symbol appears connected in parallel across the output terminals — its '+' terminal to the positive rail and its '−' terminal to ground — labelled V1, confirming that this node is the regulation feedback point where the output voltage should read 12.0 V ± 0.5 V under full load conditions.
Key facts
- The Voltmeter symbol is a circle enclosing the letter 'V', defined in IEC 60617-08 and ANSI Y32.2/IEEE 315-1975; this symbol is identical in both standards.
- A voltmeter is always connected in parallel (shunt) across the component or nodes being measured, not in series as an ammeter is.
- The designator for a voltmeter in a schematic is V or VM, per IEEE 315-1975 and ANSI Y32.2.
- The SI unit of electric potential difference is the volt (V), defined as one joule of energy per coulomb of charge (1 V = 1 J/C), per IEC 80000-6.
- A voltmeter has two terminals: a positive terminal (+) and a negative terminal (−); measuring a positive voltage requires the '+' terminal to be at the higher potential node.
- Analog moving-coil voltmeters have an input impedance of approximately 1 MΩ; digital multimeters typically exceed 10 MΩ, making them less intrusive in high-impedance circuits.
- The same circle-with-letter convention applies to all IEC meter symbols: 'A' = ammeter, 'W' = wattmeter, 'VAR' = var-meter, 'Hz' = frequency meter, 'Ω' = ohmmeter.
- A voltmeter connected in the wrong polarity in an analog meter will cause the needle to deflect backwards (below zero); digital meters display a negative sign instead.
Diagrams that use this symbol
- 3 wire 220 volt wiring diagram
- potentiometer circuit diagram
- voltmeter circuit diagram
- the12volt com wiring diagrams
- low voltage wiring diagram
- 12 volt wiring diagram
- 24 volt wiring diagram
- 4 wire 220 volt wiring diagram
Frequently asked questions
What does the voltmeter symbol mean in a circuit diagram?
The voltmeter symbol — a circle enclosing the letter 'V' — represents a voltage-measuring instrument connected in parallel across two nodes to measure the electric potential difference between them in volts. It is a permanent or temporary measurement device shown in the schematic to indicate a voltage monitoring or test point.
What does the voltmeter symbol look like?
The voltmeter symbol is a circle with the uppercase letter 'V' centred inside it, with two terminals (one positive, one negative) exiting the circle. It is defined identically in IEC 60617-08 and ANSI Y32.2/IEEE 315-1975.
Is the voltmeter symbol the same in IEC and ANSI?
Yes. Both IEC 60617-08 and ANSI Y32.2/IEEE 315-1975 define the voltmeter symbol as a circle enclosing the letter 'V'. This is one of the few electrical symbols that is truly identical across the two standards.
Why is a voltmeter connected in parallel, not in series?
A voltmeter must be connected in parallel because it measures the voltage difference across two nodes. Its high internal impedance (1 MΩ to 10 MΩ) ensures it draws negligible current and does not significantly alter the circuit. Connecting a voltmeter in series would block most of the circuit current due to that high impedance.
What is the designator letter for a voltmeter?
The voltmeter is designated V or VM in a schematic, following IEEE 315-1975 and ANSI Y32.2 reference-designator conventions.
What unit does a voltmeter measure in?
A voltmeter measures electric potential difference in volts (V), the SI unit defined as one joule per coulomb (1 V = 1 J/C) by IEC 80000-6. Ranges typically span millivolts (mV) for sensitive circuits to kilovolts (kV) for high-voltage systems.
How do I read the voltmeter symbol on a schematic?
Find the circle-with-V symbol and trace its two terminals to identify the two nodes being measured. The '+' terminal connects to the higher-potential node; the '−' terminal connects to the reference node (often ground). The symbol is connected across a component or branch, not inserted in line with the current path.
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