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102808_CAPAC_MANUAL_MODEL_90W12D_SYSTEM.doc
5. To check the operation of the controller, disconnect the reference cell and
anode leads and make the connections as shown in Figure 5.2A. The 1.5V
dry cell should be connected with a 1000 ohnm 2 watt potentiometer or
variable resistor with dial knob. With this hook-up any desired potential can be
set into the reference input by adjusting the potentiometer until the desired
value is reached as read on the CAPAC
®
Monitor. The 10 ohm 20 watt
resistor will act as a dummy load and represents the resistance of the anode.
Vary the potentiometer according to the graph (Figure 5.2B) and note that
output voltage for your model as read on voltmeter (V).
For example, if a model 37180-3 is being tested, the output of the controller as read
on Voltmeter (V) should be 5V DC when an input of 0.65 volts appears across the
reference cell input terminals. If an input of 0.60 volts or less appears across the
reference cell input terminals the output voltage of the controller should be 10 ± 2V
DC. If an input of 0.709 volts or greater appears across the reference cell input
terminals the output voltage of the controller should be 0 volts.
Detailed Service and Theory of Operation
Anode:
The anode is constructed of 1 2-1/2 inch diameter platinized titanium disc that is supported
and electrically insulated from the hull by a fiberglass holder. The platinized titanium disc
must never be painted. The current delivered by the anode depends upon the anode
voltage and the resistance of the sea water. With 12 volts applied directly to the anode, it
will deliver up to 5 amperes in warm seawater, 3 amperes in normal seawater, and as little
as .01 ampere in fresh water. It is recommended that the anode voltage not exceed 12V
DC.
If damage to the platinum surface of the anode is suspected the anode current can be
compared to that of other anodes on the boat (when there are more than one) or to a new
anode suspended in the water. Connect the anode directly to the 12 volt battery. If it’s
current is 80% or less than another anode it should be replaced.
NOTE: The anode may be identified from the inboard side by means of the 10
inches
of black lead wire attached to the back of it.
Reference Electrode
The reference electrode is constructed of a silver-silver chloride element that I
supported and electrically insulated from the hull by a fiberglass holder. In order to
assure accurate results, the silver screen must never be painted. If it should
accidentally be painted, the paint should be removed with a chemical solvent.
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