Avtron Model T477W Bonding Meter
with B14703 Battery Pack Replacement Instructions
Part Number T477WC15292
Operating Instructions
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.
2-6
C A U T I O N
The T477W Bonding Meter accuracy is significantly affected by the presence of
direct current (DC) potentials on the unknown resistance. The presence of DC
potentials at or on the unknown resistance causes saturation of the output and
input transformers. Some small DC potential is tolerated; however, that potential
varies with the magnitude of the unknown resistance. DC potentials on the order
of 10 millivolts per milliohm cause no problem. When in doubt about the
presence of DC potentials, do not use the T477W Bonding Meter. Significant
meter damage may result.
2.14
Battery Endurance
The T477W is powered from internal rechargeable batteries. Battery endurance depends on capacity (amp/hours) which is
affected by the following factors:
Temperature -
Capacity is rated for room temperature operation (25
o
C) and is tested for operation at –15 and
60
o
C. Operation above room temperature causes significant reduction in capacity.
Charge History - Capacity is based on a full charge within 10 days. To minimize charge loss (as much as 25% in
one month), batteries must be charged frequently. However, charging a battery repeatedly prior to
the “LO BAT” being illuminated in the display will cause a loss of endurance as the battery
develops a memory, which is characteristic of nickel cadmium cells. (Memory can sometimes be
erased; see Section 7.)
Age -
The battery ages after many charge/discharge cycles. Its ability (capacity) to sustain a load after a
full charge is diminished. Thus the meter has a shortened operating time before a recharge is
necessary.
Battery endurance is rated under the worst conditions (50% capacity) to provide eight (8) hours of continuous operation
providing the battery has been charged not more than 10 days prior to the time of operation. New batteries (100% capacity)
are anticipated to have sufficient energy to make twice the rated measurements. Because the T477W has a built-in timer for
automatic shutdown after 52 seconds, "Continuous Operation" is defined in terms of the following 3-minute measurement
cycle:
26 seconds current probes connected to load
26 seconds current probes not connected to load
(including 2 seconds lamp operation)
128 seconds shutdown
Total:
180
When the battery is nearing discharge, a "LO BAT" indication is displayed on the left side of the meter display. Meter
readings remain accurate, but the batteries
should
be recharged.
