Construction - GE CLPG12C Instructions Manual

GEI-8391O
CONSTRUCTION
The three main units (G1, G2, and GO) of the elPG12e relay covered by these
instructions are of the induction-cup construction.
This is the top unit of the eLPG12e relay.
It
has two electrically separate
contacts. The right-hand (front view) contact is closed when the unit is de-
energized. When energized, the unit operates to open its right-hand contact and
then closes its left-hand contact.
The four corner coils of the unit consist of two windings each. The inner
windings consist of a large number of turns of fine wire, and the outer windings
have a few turns of heavy wire. The inner windings are connected in series with a
capacitor to form a phase-shift i ng ci rcu it. The outer wi nd i ngs are connected in
series internally, and into the operating-current circuit externally. The four
side coils are similarly connected into the operating-current circuit.
To increase the torque output for sensitive settings of the Gl unit (1-2 times
minimum pickup), there is provided in the elPG12C relay a 2:1 autotransformer. The
transformer, when connected as a step-up transformer, effectively doubles the
current in the G1 unit.
The increased torque thus requires additional control-spring windup, thereby
i ncreas i ng the force on the norma lly-c lased (carri er-start) contact. The net
result is to reduce or eliminate the possibility of spurious carrier signals due to
shock or vibration when sensitive settings are employed on this unit.
As a further aid in reducing the possibility of spurious carrier signals, the
carrier-start contact is of the low-gradient construction.
The low-gradient contacts of the Gl unit are shown in Figure 5. Both the
stationary and the moving contact brushes are made from low-gradient material.
When subjected to vibration they tend to follow one another, thus resisting contact
separation.
The contact d i a 1 (A) supports the stat i onary contact brush (B) on whi ch is
mounted a conical contact tip
(e).
The moving-contact arm (0) supports the moving-
contact brush (E) on which is mounted a button contact tip (F). The end of the
moving-contact brush bears against the inner face of the moving-contact-brush
retainer (G). Similarly, the end of the stationary-contact brush bears against the
inner face of the stationary-contact-brush retainer (H).
The stop (J), mounted on
the contact dial, functions to stop the motion of the contact arm by striking the
moving-contact-brush retainer after the moving- and stationary-contact members have
made contact. The stationary-contact support (K) and the contact dial are
assembled together by means of a mounting screw (l) and two locknuts (M).
The normally-open contact is of the standard barrel type of construction.
The barrel-type contacts shown in Figure 6 are especially constructed to
suppress bouncing. The stationary contact (G) is mounted on a flat spiral spring
(F) backed up by a thin diaphragm (e). These are both mounted in a slightly
inclined tube (A). A stainless steel ball (8) is placed in the tube before the
diaphragm is assembled. When the moving contact hits the stationary contact, the
energy of the former is imparted to the 1 atter and thence to the ball, whi cn is