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Vanguard DigiTMR S2 User Manual

Page 10

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DIGITMR S2 USER’S MANUAL

REV 1

5

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 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 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 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’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.