Hitachi 152SO, Installation & Operation Manual, Page: 15 / 36

PN-152SO Switch Overload Relay
Copyright 2019 SM 5929 Rev. 23, March 2019 4-1
4. SHOP MAINTENANCE
4.1. Adjustment and Calibration
4.1.1. Operating Relay
a. The air gap between the armature and the core should be between 0.007 to
0.010 inch.
b. The armature stroke at the free end of the armature insulation should be 0.105 ±
0.003 inch.
c. The two load springs should be adjusted to exert a pressure of approximately 7
grams each on the armature in the deenergized position. This pressure may be
changed as required to meet relay calibration values.
d. The heel spring should exert a pressure of approximately 13 grams against the
armature in the deenergized position.
e. The front contact spring should have an initial pressure of approximately 10
grams against its stop, measured at the contact tips, and should have an opening
of approximately 0.070 inch with the relay deenergized.
4.1.2. Stick Relay
a. The air gap between the armature and the core should be approximately 0.004
inch.
b. The armature stroke at the free end of the armature insulation should be 0.080 ±
0.002 inch.
c. The continuity contact should be adjusted as follows:
1. The front contact (lower) spring should be adjusted to exert a pressure of
from 10 to 15 grams on the armature in the deenergized position.
2. The opening between the front contact and the heel (upper) spring should be
from 0.020 to 0.025 inch with the armature in the deenergized position. At the
same time the heel spring pressure should be adjusted so that the back
contact tip just touches its lower stop and the upper stop should be adjusted
to just touch the heel spring.
3. Adjust the back contact opening to be from 0.015 to 0.020 inch with the
armature in the energized position by bending the loop at the end of the back
contact spring.
4. Adjust the back contact spring to exert an upward force of from 20 to 25
grams against the lower stop with the armature in the energized position.
Recheck the heel spring pressure.
5. With the armature in the energized position and all adjustments completed,
the opening between the back contact buttons and the lower stop is an
approximate measure of the mid-stroke overlap of the contacts. This should
be at least 0.010 inch.