Practical guides to the tests Megavar engineers run on high voltage plant: what each test measures, which standards apply, how the test is set up and what the results mean. Every guide has a PDF version to download.
Secondary isolation separates the protection, control and metering circuits under test from the circuits that stay in service.
Power quality testing logs voltage and current at a point of connection for days and analyses the record for voltage, unbalance, harmonics, flicker, dips, swells, interruptions and transients.
Electrical thermal imaging finds connections, contacts and components running hotter than they should, on energised plant, without touching it.
Circuit breaker testing confirms a breaker opens and closes on command, fast enough and with its poles together.
SFRA testing sweeps a low-voltage signal from 20 Hz to 2 MHz through a transformer winding and records a trace that is a fingerprint of the core and winding geometry.
Protection relay testing proves that the relays guarding a substation, feeder or generator will trip when they should and stay stable when they should not.
CT testing proves that a current transformer has the ratio and polarity on its nameplate, a healthy magnetic core and sound secondary insulation.
Partial discharge testing finds insulation defects in HV cables, switchgear and transformers before they fail.
Transformer testing covers a defined set of electrical, dielectric and oil tests that together prove a power transformer is fit to energise and track its condition in service.
Earth resistance testing shows whether an earth electrode or substation earth grid will carry fault current safely into the ground.
Ductor testing measures the resistance of circuit breaker contacts, busbar joints, cable lugs and earth bonds in micro-ohms.
An insulation resistance test applies a steady DC voltage across insulation and measures the small current that flows.
VLF testing applies AC at 0.1 Hz to an MV or HV cable to prove its insulation, joints and terminations.
Battery testing shows whether a stationary standby battery can carry its DC load when the AC supply fails.
Hipot testing applies a voltage well above the operating voltage to insulation for a set time to prove it withstands it.
VT testing proves that a voltage transformer delivers a true, correctly phased image of the primary voltage and that its insulation and secondary circuit are fit for service.
Cable fault location finds the point where a power cable has failed so it can be repaired in one excavation.
