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contacts on the ends of the blade should approach
the jaw fingers at the same time and the blade
should hit both stops at about the same time. Also
the blade contacts, as they enter the jaw contacts,
should not rub the jaw fingers. If the blade rubs
the top fingers on one jaw and the bottom fingers
on the other, then a little adjustment at the bottom
of the center insulator stack with the shims of
leveling screws provided will usually result in
proper entry. If the blade rubs the top fingers on
both jaws or the bottom fingers on both jaws, then
a change in elevation is required and can be
achieved at the center stack of jaw stacks by using
the same shims of leveling screws. At this point,
recheck the blade penetration to see that the blade
hits both stops at the same time. If it doesn’t, the
shims and leveling screws will provide for
necessary adjustment.
When blade entry is satisfactorily achieved then
check to see if all jaw fingers are contacting the
blade end contact. If necessary, adjust with either
shim or leveling screws at the base of the jaw
insulator stacks. If it is expected that the
conductors to be attached to the terminal pads will
impose an appreciable force, it is recommended
that the jaw insulator columns be adjusted so that
the jaw fingers end up slightly off center on the
blade contact in a direction opposite to the
expected force. The jaw mounting bolts may now
be tightened.
6—2 Blade Contact Angle
The blade contacts can be at a slight angle in the
closed position, (Fig. 4). An allowable contact
angle of 4 degrees permits an (dimension X) is
1/16” for each 1” of contact width. Example: If
contact width (A) is 4 1/2”, then dimension (X)
can be as much as 9/32” and still be within the
plus or minus 4 degree tolerance. Fig. 4 shows the
top of the blade contact leaning to the left. It is
also permissible for the top of the blade contact to
lean to the right as long as the 4 degree angle is
not exceeded. It is common to have both
situations on one three-pole switch. In fact, after
all three poles have been adjusted in the open
position, and then closed, you may find that one
pole will be high on the right, one fairly level and
one high on the left. This is due to many variables
and tolerances plus the free play or clearance in
pin connections of all the switches and control
parts.
6—3 Blade Engagement When Switch is Closed
Due to varying friction and deflection, the distance
between the blade and its stop (dimension H in Fig.
4), with the switch fully closed, may vary from 0”
to 1”. Insulator stacks can be adjusted to achieve
this. It is not usually possible to get this dimension
to be equal on all poles of a three-pole switch.
6—4 Stops on Current Carrying Parts
The stops on the blade mechanisms are set at the
factory and seldom require any adjustment.
However, if these stops prevent the blades from
turning to an acceptable closed of open position,
they should be re-adjusted.
After each pole has been adjusted, the open and
close stop bolts at the base of the rotating insulator
column should be set.
Step 7—Install Interphase and Offset Crank Rods
With all blades in the closed position, install the
interphase rods and offset crank rod as follows:
a.
Lengthen the interphase rods that are in
compression during opening, as much as
possible, yet allowing for the pins to be
inserted.
b.
On the rods that are in tension during opening,
shorten them as much as possible, yet allowing
for the pins to be inserted.
c.
The offset crank rod between the outboard
bearing and the driven switch should be
handled the same way
Step 8—Install Vertical Operating Pipe
Attach vertical operating pipe to rotor bearing shaft, of
to offset rotor bearing shaft, with coupling pins
supplied. At this point, check drawings for accessory
equipment (auxiliary switches, mechanical interlocks,
position indicators, ground straps, etc.) which mounts
on vertical operating pipe and install before continuing
installation. The vertical pipe is predrilled at one end
for a 5/8” diameter pin, two of which are shipped,
together with a coupling, in a bad, for connection to
the offset bearing shaft (or on the pole unit rotor
bearing in the case of direct connection switches)
Summary of Contents for TTT7
Page 1: ...IB TTT7 May 2012 ...
Page 7: ...6 P a g e ...
