The takeaway
Impedance trends warn early.
Full discharge confirms capacity.
Records matter as much as readings.
01Why it matters in the field
Every hour a feeder stays dark costs a utility revenue, trust and crew time. Testing a substation battery bank is one of those jobs where a careful method saves far more time than it takes.
Most of the delays we see on site don't come from the instrument — they come from skipped preparation, unclear records and guesswork about the network.
“A reading you can't repeat isn't a measurement. It's a guess with a number on it.”
02The method our engineers use
Start with the drawings and the last known test record. Isolate, earth and discharge before anything is connected, and confirm it with a second person.
Take a baseline reading, then repeat it. Two matching readings are worth more than one perfect-looking one. Record conditions — temperature, load, weather — alongside the number.
03What good results look like
A good result is one another crew could repeat next year and get the same answer. That's the standard we calibrate our instruments to, and the standard we train crews to.
Facing this on your network?
Talk to a CSD application engineer.
