C.P. SENTINEL AUTOMATIC TYPE CATHODIC PROTECTION RECTIFIER MANUAL
INTEGRATED RECTIFIER TECHNOLOGIES, INC.
Doc #: APC0010
Rev. 3.0, November, 2004
Page 21 of 22
Faulty Connections: Often broken or high resistance connections will lead to no
rectifier output or intermittent output. Disconnect power, check and re-tighten all
connections. Be especially aware of any oxidized, burnt or discoloured
connections. Repair or replace as required.
DC voltage at output lugs, but no current
: The principle reason for this failure is
a broken CP system cables beyond the rectifier. Investigate and repair broken
cables.
DC voltage at output lugs, current flowing to load, but no current reading on
ammeter: This could be the result of a defective ammeter, faulty leads, or
failure of a metering switch. Repair or replace defective components.
Failure of Reference Electrode
: The SENTRY Controller is equipped with “Loss
of Reference Electrode” shut-down circuitry to prevent coating damage due to
excessive polarization upon failure Reference Electrode. Replace defective
Reference Electrode and re-energize rectifier. Refer to Page 7.
B. LIMITED RECTIFIER OUTPUT CURRENT: This fault may be caused by any one or more
of the following conditions:
Improper Mode settings
on the SENTRY controller resulting in insufficient
current to the CP system. Re-check settings and limits for current, voltage and
potential (If applicable).
Load resistivity too high
for rating of the rectifier. This will usually be indicated
by a “Voltage Limit” condition; where the Red LED is illuminated. Check anodes
and ground bed resistance. Modify if necessary, or replace rectifier with a
higher rated unit.
Low supply voltage
: Check incoming AC voltage to rectifier while rectifier is
under load. Consult electrical maintenance personnel for adjustment if line
voltage is low.
Excessive AC interference
on Reference Electrode to Structure inputs may
reduce the rectifier DC output (on Potential controlled rectifiers). Although
equipped with circuitry to minimize AC interference on the potential measuring
circuit, excessive amounts of interference can cause the SENTRY Controller to
reduce output current or voltage in response to this outside interference.
Review installation practices outlined on Page 7.
Failure of SCR-Diode module
: could result in “half-wave” output, which will yield
only half of the rated output. Replace defective module with replacement.
Failure of the SENTRY Controller board
. Remove defective board & replace
with known working control board.
C. POTENTIAL SET POINT NOT MAINTAINED: This fault may be due to one or more of the
following conditions:
Rectifier output being limited
by either the Voltage Limit or the Current Limit.
Adjust these limits to the maximum rating of the rectifier.
Rectifier output being limited
by the Manual Tap adjustment (On rectifiers
equipped with this option) Sufficient voltage must be supplied from the
transformer taps to maintain the set point potential.
Failure of the Reference Electrode
results in limited or no output. See Page 7.
Excessive AC input on Reference Cell
– Structure leads. See Item “B”, above.
Defective “Press-to-Set” selector switch
. Oxidized contacts could result in the
“Set Potential” not being switched correctly into the SENTRY Controller.
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