Vanguard DigiTMR S2 PC User Manual

Page 6

DIGITMR S2 PC USER’S MANUAL

REV 1

1.2 Operational

Modes

1.2.1. “On-Line” Mode

In “On-Line” mode, the trip/close time is derived from the time of trip, or close-coil initiation, to
the breaker’s bushing current-break-or-make as detected by an AC clamp-on current sensing
probe. The DigiTMR S2 PC can time a circuit breaker’s OPEN operation by sensing the time when
the OPEN coil is energized until the bushing CT current returns to zero. The breaker’s CLOSE time
is detected when the close coil is energized until the bushing CT current is detected. The “On-Line”
mode provides a quick way to diagnose a breaker’s performance and can reduce maintenance
costs.

1.2.2. Time-versus-Travel Circuit Breaker Analyzer Mode

In Time-versus-Travel mode, the DigiTMR S2 PC applies a test voltage of 35 Vdc to each of the
contact channels, thus allowing an analog to digital converter (A/D) to determine a close, open,
or an insertion resistor as the state of the contact. The DigiTMR S2 PC records into memory
20,000 readings (in on second) from the A/D’s and the transducer position counters. The
contact time, circuit breaker stroke and velocity are then derived from the stored data.

NOTE

The DigiTMR S2 PC’s travel transducer employs optical encoders to send quadrature
signals to the unit’s counters. With the use of digital transducers and counters, the
need to setup or calibrate the transducers is eliminated.