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TORQUE CHART
The table below serves as a guide or suggestions for nominal torque
values for bolted electrical connections.
based on individual joints, material and quantity of fasteners,
lubricated or not.
BOLT
TYP TOL
ALUM
SIZE
+/- NOM
IN
1/4-20
+/- 20%
50
5/16-18
+/- 20%
85
3/8-16
+/-20 %
145
1/2-13
+/-15 %
300
5/8-11
+/-15 %
480
3/4-10
+/-15 %
720
NOTES:
1.
Always use two wrenches when tightening or loosening bolted
connections to prevent damage.
2.
Tighten, wait several seconds, then re-tighten all connecting lugs
and bolts.
3.
Torque values are in pounds.
CONNECTIONS
The transformer has both high voltage (HV) and low voltage (LV)
winding connections. Multiple tap positions are available on the HV
winding to allow for adjustments, which may be necessary
because of the specific supply voltage or transformer load
characteristics.
If
tap
adjustments
"CHANGING TAPS" section below. Connection points are clearly
labeled on the transformer. Refer to the nameplate and
diagram to make the electrical connections. Never attempt to
make
any
connections
nameplate/connection diagram.
When making connections between plated aluminum transformer
terminals and copper or aluminum conductors of associated
equipment, the following procedure is recommended.
Assemble a spring washer and a flat washer under the head of
each bolt. Place the spring washer so that the concave surface is
away from the bolt head and the periphery is on the flat washer.
The flat washer prevents the outer edges of the
from
cutting
through
the
forces.
Place a flat washer under the nut on the opposite side of the joint
and tighten the nut until the spring washer is just flattened. (Washers
are flattened when there is a noticeable increase in bolting torque.)
After the nut has been properly tightened it should be locked
with a locking
nut or such other locking device as may be
furnished with the equipment being connected to the transformer.
When clamp-type terminals are assembled on plated aluminum bars,
the same basic procedure given above should be followed except
Torque values may vary
SIL BRONZE
FT
IN
FT
IN
4
60
5
75
7
110
9
135
12
195
16
240
25
420
35
540
40
840
70
1080
60
1200
100
1560
are
necessary,
that
are
not
indicated
spring washer
plating
and distributes the bolting
that the spring washer and flat washer should be placed on the nut
on the eye-bolt and the bar.
When connecting bus bars, be sure the joints are properly aligned
prior to bolting to prevent excessive strain on the insulators.
a terminal chamber, long sections of unsupported conductor should
be avoided and leads should be flexible enough to allow for
expansion and contraction.
STEEL
For electrical connections, see "SURGE PROTECTION" on page 3.
FT
GROUNDING
6
11
The core and coil structure is connected to the enclosure by
means of a flexible connector. This connection must be tight at all
20
times.
45
Grounding must be in accordance with NEC and all applicable
90
state and local codes. A NEMA Standard stainless steel ground
130
pad with two tapped holes is provided on the base assembly for
connecting the transformer enclosure to ground.
and thoroughly reliable connection should be made between
the pad and a low resistance ground through a conductor of
adequate cross section.
CHANGING TAPS
CAUTION:
transformer before removing the panels to change taps
could result in serious personal injury or death.
NOTE: Do not bend tap terminals or position the hardware
in a manner that would reduce clearance between or cause
damage to tap terminals.
To change the tap position:
see
the
1.
De-energize a n d p r o p e r l y g r o u n d the transformer
following the safety messages above and your company's
wiring
lock-out/tag-out procedures.
on
the
2.
Remove the enclosure panel or door to access the
transformer high voltage windings.
3.
Use an appropriate grounding device to ground the coils
and discharge any static charge.
4.
Locate the tap jumpers.
5. Change the tap jumpers on each phase to the appropriate
tap connection.
same tap position for three phase transformers.
6. Torque the tap connections.
NOTE: For multiple voltages or other special
arrangements,
connection diagram.
7.
Inspect the enclosure to ensure all hand tools, equipment, or
any other foreign materials are removed from the enclosure.
8.
Re-install the door or enclosure panel.
Make no connections other than those authorized by the
nameplate.
- 4 -
Failure to de-energize and grounding the
The
tap
jumpers
see the transformer nameplate and/or
MIT100-15A
In
A substantial
must
be
on
the
6/2011
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