Avtron Model T477W Bonding Meter
with B14703 Battery Pack Replacement Instructions
Part Number T477WC15292
Calibration and Maintenance Procedures
Subject to the EAR, ECCN [9E610.a].
This information is subject to the export control laws of the United States, specifically including the Export Administration Regulations (EAR),
15 C.F.R. Part 730 et. seq. Transfer, retransfer, or disclosure of this data by any means to a non-U.S. person (individual or company), whether in the United States or abroad, without any
required export license or other approval from the U.S. Government is prohibited, including without limitation any diversion to a military end user or use in a military end use application.
4-3
4.3
Calibration Period or Frequency
As the manufacturer, Avtron suggests a calibration interval of one year. However, it is the sole responsibility of the end user
to determine an interval that satisfies their quality system requirements.
4.4
Maintenance
The T477W is composed of solid state components and requires minimal maintenance. Field repairs are not recommended.
Component substitution with other than approved Avtron parts may impair intrinsic safety, thus voiding the UL approval and
putting property and people at risk. It is recommended that a malfunctioning meter be returned to Avtron for repair.
W A R N I N G
Please note that breaking the tamper seal on the T477W Bonding Meter for any
reason whatsoever shall relieve Avtron Aerospace, Inc., of any and all liability
with regard to personal injury or property damage, whether directly or indirectly
resulting from the use of the meter. Warranty claims on meters with a broken
tamper seal may be honored only after an evaluation of the meter is performed by
Avtron.
4.5
Preventive Maintenance
The T477W is powered by rechargeable nickel cadmium batteries.
The battery pack is the most likely component in the T477W to require maintenance. The pack is potted to ensure proper
operation of current limiting resistors which were required for safety certification by Underwriter Laboratories. The potting
makes battery replacement awkward and expensive, but it is necessary for safety. Battery preventive maintenance procedures
have been developed to identify battery problems before they become serious.
Nickel cadmium batteries are reliable and will provide hundreds of charge/discharge cycles. Relatively frequent use is
recommended and batteries should be discharged to the point the “LO BAT” indicator is displayed before recharging. The
most common battery problems anticipated are over-discharged, overcharged, and short cycled batteries.
Over-discharge occurs when the T477W is used following the "LO BAT" display. Over-discharging may cause batteries to
become depleted to the point where one or more battery cells have reversed current flow. Furthermore, extremely deep
discharge may obstruct automatic shutdown of the meter display.
Overcharging occurs when the T477W is placed on charge continuously for weeks or months. This will cause some drying of
the battery and the possibility of reduced capacity.
Short cycled usage is encountered when fully charged batteries are partially discharged and then fully recharged. Short
cycling causes battery capacity to be progressively reduced and has been referred to as memory conditioning. Generally, but
not always, a reconditioning process in which the battery is given several deep discharge/charge cycles corrects a short cycled
memory.
