JANUARY 31 2003
voltage is also half of normal, proceed to paragraph 5-2.7 to troubleshoot the
diodes/selenium plates. If voltage is normal, proceed to paragraph 5-2.8 to troubleshoot
the anode bed.
If the current is normal and the rectifier ammeter reads significantly
, either the shunt, the connections,
or the ammeter
is faulty (proceed
paragraph 5-2.2.3a). If the current is normal, the rectifier ammeter reads normal, and
structure potentials are still significantly changed from normal, proceed to paragraph 5-
a) Measure the DC current with a handheld multimeter connected in series
and with the meter on the DC amps scale. Disconnect anode header cable at P4 and
measure current from P4 to anode lead. Compare the measured current value to the
current value taken in paragraph 5-2.2. If values are significantly different, replace the
shunt. If values are the same, proceed with paragraph 5-2.2.3b.
WARNING: AC voltage is still present inside the rectifier with the rectifier circuit breaker
or power switch OFF. All connections inside the rectifier cabinet should be made with
alligator clip leads connected with the power to the rectifier OFF. If needlepoint leads
are used with power ON, observe prudent electrical safety practices for working with live
b) With power OFF, check for loose connections from N2 through N9,
including any press-to-test switch or button, and continuity of all wires between those
points. This will require disconnection of AC power from the rectifier cabinet and
possibly removal of the rectifier from the cabinet. Note that loose connections are
characterized by heat, discoloration of the connection, and melted insulation. Repair or
replace loose connections and replace damaged or broken wires. If problems are not
found, proceed with paragraph 5-2.2.3c.
c) With power OFF, remove ammeter from rectifier. This will require
disconnection of AC power from the rectifier cabinet and possibly removal of the rectifier
from the cabinet. Disconnect one end of the resistors on reverse side of meter.
and compare to the value of the resistor (if no resistors are present, replace meter).
Replace resistor or meter as required.
d) Normal current values accompanied by loss of potential shifts indicate a
change in the protected structure. If the protected structure is isolated, check all
dielectrics and repair or replace faulty ones. If the protected structure is not isolated,
check for additions to the protected structure, or new structures in the area which are
continuous with the protected structure, increase current to protect larger structure(s),
isolate other structure(s), or install additional impressed current system(s) as required.