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TRUCK SERVICE MANUAL
TM 5-4210-230-14&P-1
ELECTRICAL
Fig. 8 Construction of Condenser
Heavy-duty
condensers
require
more
insulation
between foil sheets of the winding. Since heavier insulation
also increases the distance between foil sheets, more foil area
is needed to obtain the same capacity. This is accomplished
by using a larger assembly, Fig. 9.
Fig. 9 Comparison Between Standard and Heavy-Duty
Condenser
The quality of insulation in a condenser is checked on a
scale reading in megohms (a megohm is one million ohms).
When all moisture is eliminated in assembly and windings are
hermetically sealed, insulating quality or dielectric strength of
insulation between foil sheets will be high. If moisture is
present in a condenser, insulation is low and may be said to
be weak. A condenser having a resistance below 2 megohms
when hot will drain sufficient
energy from ignition system to cause engine missing.
Series resistance in a condenser is usually caused by
loose or corroded connections. High series resistance causes
a condenser to be slow in taking a charge and results in
higher voltage at the separating contact points. Arcing and
rapid wear of contacts along with engine missing during
starting and low speed operation may be indications of this
condition.
Capacity of most ignition condensers used on IH trucks
is approximately .20 microfarads. This value is controlled by
the area and closeness of the foil sheets. Standard
condensers have two sheets of insulation assembled between
foils,
making
a
short
container
possible.
Heavy-duty
condensers have three sheets of insulation between foils and
because of the greater foil area required, are housed in longer
containers.
CONDENSER TESTS
To test an ignition condenser, a special condenser
tester must be used, Fig. 10. Such a tester will check
condenser for insulation breakdown, low insulation resistance,
high series resistance and capacity. All four of these are
characteristics which affect ignition performance.
Fig. 10 Condenser Tester
CTS-2013-E Page 7
PRINTED IN UNITED STATES OF AMERICA
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