GE Industrial Solutions Power-Vac ML-20 Mechanism - Manual (Page 19)

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SECTION 12—Timing
Timing and speed checks are optional and also depend on the
level of maintenance performed. Generally these tests are not
required for normal maintenance. If a new mechanism has
been installed or extensive repair, replacement or major
disassembly has been performed, it is recommended that
these tests be performed.
To determine contact velocity, a travel recorder and or an
oscillograph are required. Optional, travel recorder linkage can
be obtained through your local GE Sales Office by ordering
part number 0144D1235G002. A typical travel trace and
interpretation are shown in Figure 11.
Timing may be checked by monitoring control circuit voltage
and using no more than six volts DC and one ampere through
the vacuum interrupter contact to indicate closed or open
condition. Typical time ranges vary with coil voltage, but
nominal values are:
Initiation of trip signal to contact parting
5 Cycle Breaker 32-45Milliseconds
2 Milliseconds Maximum Pole Spread
Initiation of close signal to contact closing
45-75 Milliseconds (DC Control Voltage)
35-65 Milliseconds (AC Control Voltage)
2 Milliseconds maximum pole spread
Trip-free operation maybe checked by applying a simultaneous
close and trip signal, and a minimum re-close operation may
be checked by tripping a charged breaker open while
maintaining a close signal.
Instantaneous re-close time* 85-140 Milliseconds.
*Time from application of trip signal until breaker contacts
re-close.
Figure 11 Sample operating speed graphs
* For breakers equipped with an opening dashpot,
there is virtually no overtravel or rebound.