Definition
A high-voltage ohmmeter used to measure very large electrical resistance values, typically in the megohm range. It applies a high test voltage (commonly 500 volts or more) across insulation to detect leakage paths and verify that wiring, motors, generators, or other electrical components are properly insulated.
Plain English
A special meter that uses a high voltage to test whether the insulation around wires and electrical parts is still doing its job. If the insulation is breaking down, the meter will show it.
Context Anchor
Seen in aircraft maintenance and electrical troubleshooting, especially when checking wiring or electrical components for insulation breakdown.
Derivation
The name comes from 'megohm' (one million ohms) combined with the suffix used in early instrument brand names. The word started as a trademark (Megger) and became the common term for any insulation-testing meter.
Why Pilots Care
Insulation breakdown can cause shorts, electrical fires, or component failures in flight. A megger test during maintenance is one of the main ways those problems are caught before they reach the aircraft.
Intuition Check
A Megger is not just a regular resistance meter. It uses a higher test voltage to check insulation, so it must be used correctly and not casually connected to sensitive aircraft electronics.
Example Sentence 1
The technician used a megger to check the insulation resistance of the generator windings before returning the aircraft to service.
Example Sentence 2
Before reconnecting the battery, the technician Meggered the power leads to rule out any insulation faults.