Contact Resistance; Table 3-3. In-Service And Field Calibration Operating Values; Table 3-4. Contact Assignments; Table 3-5. Contact Resistance (Ohms) - Hitachi PV-250 Installation Operation & Maintenance

Table 3-3. In-Service and Field Calibration Operating Values

Pick Up (PU)
Full Stroke(FS) Max.
Min. Drop Away (DA)
% of Actual PU is 80%
Full Drop Away (FDA)
* If relays don't meet the Acceptance Criteria they must be shopped
for readjustment and recalibration.
Coil Connections
Old Style Base
WINDING
Location
L+
Local
L-
C1+
Control
C2-
* Contacts are standard low-voltage silver-to-silver impregnated
carbon fronts
and silver-to-silver backs.

3.3. Contact Resistance

Resistance of front contacts should be measured with the armature in its full-stroke
position, and resistance of back contacts should be measured with the armature fully
released. Cleaned contact resistance should not exceed the values shown in Table 3-5.
Type of Contact
Silver-to-Silver Impregnated Carbon
Contact surfaces should not be disturbed unless there is evidence of severe pitting from
excessive loading or an accidental short through the contacts. When contacts must be
dressed, refer to Sections 3.4.2 and 3.5.
Copyright 2019
Current
(Amps)
0.048 Min. – 0.053 Max.
0.053 Min. – 0.059 Max.
Equal to or Greater Than
80% × PU
0.028 Amps Min.

Table 3-4. Contact Assignments

New Style Base
Location
10E
10F
1A
2F

Table 3-5. Contact Resistance (Ohms)

Silver-to-Silver
SM 4574F, Rev. 4, March 2019
Acceptance Criteria*
Front contacts should be "closed"
Vane should touch upper roller
Front contacts should be "open"
Vane touches the lower roller stop
Contacts*
Type Old Style Base
Location
7F (Front)
7H (Heel)
Fronts
8F (Front)
8H (Heel)
9H (Heel)
9B (Back)
Backs
10H (Heel)
10B (Back)
Front Contacts
0.09
--
PV-250 Track Relay
New Style Base
Location
11B (Front)
12B (Heel)
11C (Front)
12C (Heel)
11E (Heel)
12E (Back)
11F (Heel)
12F (Back)
Back Contacts
--
0.03
3-7