AVTMTTR25 Rev C April 2008
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5
MAINTENANCE AND TROUBLESHOOTING
Maintenance
Maintenance should be performed only by qualified persons familiar with the
hazards involved with high-voltage test equipment. Read and understand Section
2, Safety, before performing any service.
The TTR25 test set is sturdily constructed and requires no periodic maintenance.
Routine maintenance is all that is required for the TTR test sets. Inspect the
cable assemblies occasionally to ensure they are in good condition.
The appearance of the TTR test set can be maintained by occasionally cleaning
the case, panel and cable assemblies. Clean the outside of the carrying case
with detergent and water. Dry with a clean, dry cloth. Clean the control panel with
a cloth dampened with detergent and water. Do not allow water to penetrate
panel holes, because damage to components on the underside may result. An
all-purpose, household spray cleaner can be used to clean the panel. Polish with
a soft, dry cloth, taking care not to scratch the display screen cover. Clean the
cables and mating panel receptacles with isopropyl or denatured alcohol applied
with a clean cloth.
Calibration Check
A complete performance and calibration check should be made at least once
every year. This will ensure that the TTR25 test set is functioning and calibrated
properly over the entire measurement range. The TTR25 calibration is performed
on each new or repaired unit before sending it to a customer. There is a special
TTR25 final calibration procedure which requires a NIST-traceable test
equipment to be used. As a result of such calibration procedure, each TTR25
may be NIST certified.
To check the TTR25 calibration at a customer site or in the field, the Megger
Calibration Standard Cat.No550055 or equivalent standard should be used. To
perform a quick simplified calibration check, the Megger Calibration Standard
CatNo550555 may be used. The last standard has eleven switchable turn ratio
settings which cover the turns ratio range from 1:1 to 2000:1. Using these
Calibration Standards will confirm proper calibration of TTR25.