Vanguard CT-7000 - Manual (Page 51)

CT-7000 Operating Instructions
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9.10 Breaker Travel Analysis
The CT-7000’s travel analysis includes the breaker’s stroke, over-travel, bounce-back,
contact-wipe distances and contact velocity calculations.
9.10.1 Breaker Stroke
The CT-7000 uses a digital transducer to measure a breaker's contact stroke, over-travel and
bounce-back. The digital transducer output are 200 counts per linear inch of travel, therefore the
resolution is accurate to about 1/200 inch. The output resolution is ±0.01 inch on the test result
report.
Unlike slide-wire transducers, the CT-7000’s transducer needs no calibration or setup. A user
verifies the transducer’s functionality by selecting a diagnostic test for the transducer, which is
further explained in Paragraph 9.19.
9.10.2 Breaker Over-Travel Distance
Over-travel is the distance the contact moves beyond the resting position. Over-travel is
typically found in the close operation. (See Appendix A for more details).
9.10.3 Breaker Bounce-Back Distance
Bounce-back is the distance the breaker contact moves before the resting position after the
over- travel. Again, bounce-back is typically found in the close operation. (See appendix A for
more details).
9.10.4 Contact Wipe
Contact wipe is the distance measured from the close position to the contacts touching or
parting positions. In the close operation, contact wipe is measured from the contacts touching
position to the final close position.
In the open operation, the contact wipe is measured from the close position to the contact
break or parting position.
NOTE
Contact wipe is measured during an operation. The measurement may not be as
accurate as the measurement done using the Slow-Close Mode. It is recommended
that the user use the Slow-Close Test to verify the contact wipe measurement, if
required. Please refer to Paragraph 9.18 for further information on the Slow-Close
Mode.
9.10.5 Breaker Velocity
When used with a travel transducer, the CT-7000 can calculate the breaker contact velocity
through the arc zone. Users will need to program the calculation points or analysis points on the
travel curve for the unit to calculate the contact velocity. Analysis point selections and setup are
discussed in the following paragraphs.
9.10.6 Analysis Point Selections
Analysis points are used to calculate the average contact speed through the contact's arc
zone. The analysis points are usually specified by the breaker’s manufacturers. The analysis
points can programmed into the CT-7000 by the user. The CT-7000 will store the two setup
points for calculating velocity one set each for the open and another set for the close operations.
These setups remain in the CT-7000’s memory until it is changed by the user.