Definition
An electrical instrument used to measure reactive power in an alternating current (AC) circuit, expressed in volt-amperes reactive (VARs). Reactive power is the portion of AC power that flows back and forth between the source and inductive or capacitive loads without doing useful work.
Plain English
A meter that shows how much electrical power is sloshing back and forth in an AC circuit without actually being used to do work. It measures the 'wasted' or stored electrical energy in the system.
Context Anchor
Seen in aircraft electrical-system manuals, large-aircraft AC power systems, generator checks, and maintenance test equipment.
Derivation
The name is built from VAR, the unit it measures, which stands for volt-ampere reactive. 'Meter' simply means an instrument that measures something. So a varmeter measures VARs.
Why Pilots Care
On multi-engine aircraft with paralleled AC generators, varmeter readings tell the crew whether reactive load is being shared evenly between generators. An unbalanced reading can indicate a generator problem and may require load shedding or generator isolation.
Intuition Check
Do not confuse a varmeter with a vertical-speed instrument. A varmeter measures AC electrical reactive power, not climb or descent.
Example Sentence 1
After paralleling the generators, the crew checked the varmeters to confirm reactive load was split evenly between the two units.
Example Sentence 2
An off-scale varmeter reading prompted a check of the aircraft's capacitive and inductive components.