Routine Maintenance - ABB HCB-1 Instruction Leaflet

Type HCB-1 Pilot Wire Relay System
7.3.3. Polar Unit Contact Adjustment
Place a .088 to .095 inch feeler gage between the
right-hand pole face on the armature. This gap
should be measured near the front of the right-hand
pole face. Bring up the backstop screw until it just
makes with the moving contact. Place .045 to .050
gage between moving contact and the stationary
contact on the left-hand side of the polar unit. Bring
up the stationary contact until it just makes with the
gage and lock in place. For relays with double con-
tacts make sure that both upper and lower contacts
make at the same time.
7.3.4. Polar Unit Calibration
Connect the restraint tap link in the position in which
it will be used. Connect terminals X1 and X2 of the
insulating transformer across the pilot-wire terminals
of the relay. Connect the relay taps on 4, C, and H.
The sensitivity of the polar unit is adjusted by means
of two magnetic, screw-type shunts at the rear of the
unit. Looking at the relay front view, turning out the
right-hand shunt decreases the amount of current
required to close to the right-hand stop. Conversely,
drawing out the left-hand shunt decreases the
amount required to trip the relay. In general, the
father out the shunt screws are turned, the greater
the toggles action will be and as a result, the dropout
current will be lower. In adjusting the polar units, be
sure that a definite toggle action is obtained, rather
than a gradual movement of the armature.
Start with both shunts out 4 to 5 turns. Short out the
pilot-wire on the high side of the insulating trans-
former. Momentarily apply 40 amperes from termi-
nals 5 to 3. Now remove the short from H1 to H4 and
apply current to terminals 7 and 9. Adjust the shunts
at the rear of the polar unit such that the unit oper-
ates at 2.10 to 2.15 amperes and resets at 1.0
amperes or higher.
NOTE: Right-hand shunt controls pickup while
left-hand shunt controls dropout.
After this adjustment is complete, short out pilot-wire
and apply 40 amperes momentarily from terminals 5
to 3. Now remove the short from H1 to H4 and check
pickup for I . If value has changed from before, it will
79
be necessary to re-adjust the right-hand shunt. Sev-
eral trials may be necessary before the relay will
pickup at 2.10 amperes and dropout at 1.0 amperes
or higher. In each case, 40 amperes should be
applied to terminal 5 and 3 with the H1 and H4 termi-
nals shorted before any additional adjustments are
performed on the shunt.
After the shunts have been adjusted, apply 40
amperes momentarily to terminals 3 and 5 of the
relay with the pilot-wire open. Pickup will be approxi-
mately 1.4 amperes with current applied to terminals
7 and 9. This change in pickup is due to a change in
the residual magnetism in the polar unit of the relay.
In the de-energized state, the permanent magnet of
this unit produces a flux or magnetic bias to keep the
contacts open. When the unit is energized, a second
flux (electrical) is produced which either adds to or
subtracts from the magnetic flux. When the electrical
flux is removed, the magnetic structure of the polar
unit is changed. Hence, the flux produced by an
excess of restraint current, adds to the magnetic
bias, and the flux produced by an excess of operat-
ing current subtracts from the magnetic bias. This
characteristic is inherent in the polar unit and has no
effect on the overall performance of the relay.
After the shunt adjustment has been made, change
the input current connections to terminals 3 and 5.
Apply 40 amperes momentarily with H1 and H4 ter-
minals shorted. Remove short and measure pickup
with current applied to terminals 3 and 5. The relay
should trip with I = 0.45 to 0.55 amperes.
35

8.0 ROUTINE MAINTENANCE

8.1. CONTACTS
All contacts should be cleaned periodically. A contact
burnisher, style number 182A836H01, is recom-
mended for this purpose. The use of abrasive mate-
rial for cleaning is not recommended, because of the
danger of embedding small particles in the face of
the soft silver and thus impairing the contact.
8.2. ICS UNIT
Close the main relay contacts and pass sufficient
direct current through the trip circuit to close the con-
tacts of the ICS. This value of current should not be
greater than the particular ICS tap setting being
used. The indicator target should drop freely.
41-971.3M
15