Winco W15PTOS/D - Manual (Page 9)

Page 7
60706-179-8100
Testing of Rectifiers
Unbolt the rectifier diode stud from the mounting clamp.
Move rectifier away from the metal stud.
1. Connect black lead of meter to stud of rectifier
and red lead to the solder terminal. Meter should
read a low resistance.
2. Now, reverse the lead on rectifier terminals.
Meter should read open circuit of infinite resis
tance. A shorted diode will give low resistance
reading in both directions. An open diode will give a high
resistance (infinite) reading in both directions.
Handling Procedures for Rectifier Diodes
1. Rectifier diodes should be handled in a manner which
avoids the possibility of sudden shocks being applied,
such as those encountered in dropping from a work
bench to a hard floor. Damage done to the rectifier by
such shocks may not be detected by subsequent testing,
yet may cause poor system reliability.
2. Any lead trimming or forming operations should be
done with care to avoid damaging the leads or the glass
header seals.
3. Leads should never be bent or twisted. If lead forming
is necessary the lead should be supported so that no
NOTE: THE FOLLOWING INFORMATION IS FOR REFERENCE ONLY - CONSULT A
QUALIFIED SERVICE PERSON FOR FURTHER TESTING AND REPAIR.
TRACTOR DRIVE WINDING RESISTANCES
ROTATING FIELD TRACTOR DRIVE
ROTOR STATOR CAPACITOR
MAIN POWER POWER AUX. 450 VAC
MODEL T1-T2 T3-T4 Z1-Z2
W15PTOS/C 3.124 0.0893 0.0893 0.503 101.5 MFD
bending occurs closer than 1/8 inch to the rectifier body,
and that header seals are not fractured or broken. If this
seal is broken, it removes mechanical support for the lead
and allows entry of moisture into the rectifier, almost
assuring early failure.
4. Care must be taken during all soldering operations. It
is unsafe to exceed the general specification to which
diodes are tested for solder ability. This is 10 +/- 2
seconds at a temperature of 230°C + 5°C at a point 1/16
+/- 1/32 inch from the diode body. This is not as restric-
tive as it may sound, since 230°C is 446°F and 60/40
solder melts at 375°F, and with proper procedure and
soldering tools a solder joint can be made in 4 to 7
seconds. Also, solder joints are almost never made this
close to the diode body. Heat sinks, such as a pair of
needle nose pliers or alligator clips, can be attached to
the lead between the solder joint and the diode body to
further reduce the possibility of heat damage.
Also, precautions should be taken to prevent solder or
flux bridging which causes a conductive path across the
case of the rectifiers. As a precaution all flux should be
removed by using alcohol and a small brush. Pay
particular attention to assure that glass header seals are
free of all flux.
Testing Stator
1. Instrument required - Volt-Ohmmeter. Set on Ohm
X1 scale.
2. Check Ohmmeter by touching leads together.
Reading should be zero.
3. Tag and lift control wires from stator winding(s) to be
checked.
4. First, check if stator winding(s) are grounded
a. Connect one lead of Ohmmeter to ground.
b. Touch other lead to each stator wire. Meter
should stay at infinite (not move).
c. If reading is indicated, stator is grounded and
should be replaced.
d. Check all three windings.
5. Second, check stator windings for opens.
Symptom: when generator was running, no voltage
on one line to neutral.
Stator - 6 Wires - 3 Windings 1 Phase
This armature has two power windings and one excitation
(auxiliary) winding.
1. Connect ohmmeter one lead to T1-red. Other lead to
T2-green. Meter should read near zero. Then other lead
to T3-black. Meter should read infinite. Then other lead to
Z1-white. Meter should read infinite.
2. Connect one lead to T3-black. Other lead to T4-yellow
Meter should read near zero. Then other lead to Z1-white.
Meter should read infinite.
3. Connect one lead to Z1-white. Other lead to Z2-brown
Meter should read near zero