
Lucent Technologies Lineage
®
2000 125A Ferroresonant Rectifier J85502C-1
Issue 8 July 1999
Troubleshooting and Adjustments 7 - 9
7. While holding the meter selector switch in the BATT V
position, use a jeweler’s screwdriver to adjust R15
potentiometer so that CM3 meter and the DMM connected
to the rectifier test points agree within ±0.02 volts.
8. Release the meter selector switch. The switch should
automatically return to the AMPS (center) position.
9. Disconnect the DMM from the rectifier REG test points.
10. Connect DMM to the rectifier output terminal and ground,
see Figure 5-4.
11. Observe and record the voltage indications on the DMM
and the rectifier meter as the meter selector switch is
moved to the indicated positions as shown in Table 7-B.
12. If the rectifier meter does NOT meet the tolerances,
replace the CM3 meter board per “Replacing CM3 Digital
Meter Board” in Section 8. Repeat this procedure from
Step 1.
Table 7-B: Digital Meter Tolerance
Meter Position
Tolerance
RECT V
±0.5 volt for Series 1 or 2 CM3 boards.
±0.2 volt for Series 3 CM3 boards.
AMPS
± percent of rectifier rating.*
Notes:
To compare, measure the shunt voltage. 1mV of shunt
voltage indicates 3.125A of output current. Example: the
shunt voltage should be 40 mV at full load, 125A. At 125
percent of full load, the shunt voltage should be 50 mV. (See
“Backup High Voltage Shutdown (HVSD) Test (On Line)”
in Section 6.
To verify CM3 digital meter’s accuracy, measure the shunt
voltage between E1 and E2 on CM1. 1mV of shunt voltage is
equivalent to 0.625 ampere of output current; i.e., at 12.5
ampere or 25 ampere load, the shunt voltage should read
20mV or 40mV respectively (20 x 0.625 = 12.5; 40 x 0.625
= 25). If CM3 does not display the current within ±2.5% of
the actual measured and calculated current, adjust R15 on
CM3.