By Jay Prigmore II, Ph.D., P.E. Published · Prepared and reviewed by a licensed Professional Engineer
What failed, how it failed, and what the evidence looked like. Each note is drawn from forensic investigation experience and generalized so that no client or matter can be identified.
By Jay Prigmore II, Ph.D., P.E. Published · Prepared and reviewed by a licensed Professional Engineer
Paralleled standby generators that start on a utility outage and then trip on loss of excitation: reversed CT polarity and mismatched voltage regulator settings.
Read →Repeated critical-bus outages traced to zone-selective interlocking left enabled on breaker trip units because a self-restraint jumper was never installed.
Read →Nuisance operation of PV combiner box string fuses at normal load current: reading the fuse ribbon, temperature-rise testing, and NEC 690.8 sizing.
Read →How a corroded aluminum-to-copper bolted bus joint became a high-resistance connection, overheated, and ignited its boot inside a generator excitation cabinet.
Read →Why a generator's main breaker cannot protect against a fault on its own line side, and why generator fault current may never reach the breaker's trip settings.
Read →Answering a power quality complaint with measurements that hold up: Class A metering at the PCC, baseline and seasonal tests, and percentile compliance.
Read →