Fusing Equipment
NX® Fuses with Arc-Strangler Switch
Equipment Specifications
Reference Data
R240-60-11
Replaces 243-10BA-2
NX FUSES WITH ARC-STRANGLER LOAD BREAK
F o r convenience i n specifying desired equipment o n
various jobs, a s e t of s u g g e s t e d s p e c i f i c a t i o n s for
the l i n e of NX® f u s e s and switches is presented below.
T h i s equipment c a n b e u s e d i n any indoor installation
where:
1. Silent operation i s d e s i r a b l e
2. Load break is required
3 . Smaller s p a c e requirements will s a v e on installation
costs
4. Hook s t i c k operation i s allowed
5. High interrupting rating is needed
6. Complete a b s e n c e of expulsion g a s e s i s advantageous
Indoor i n s t a l l a t i o n s a r e defined a s a n y e n c l o s u r e
which protects t h e equipment from direct weather. T h i s
includes :
1. Pad-mounted transformers
a . Oil-filled
b. Dry type
2. F r e e s t a n d i n g e n c l o s u r e s
3. Building v a u l t s
4. High r i s e building primary feed compartments
5. Underground v a u l t s , nonsubmersible with overhead
covering
T o s p e c i f y any particular s i z e or variation, s e l e c t and
combine:
I. F u s e Specification
Note: Current and voltage rating of fuses must be
c a l l e d out on individual inquiries or jobs.
and/or
II. Switch Specifications
a n d o n e of t h e f o l l o w i n g
111. General and Mounting Specifications for S i z e and
Variation of Mounting Desired
A. Single- Phase Unit
B. T h r e e - P h a s e Unit
C. Single- Phase, 3 - P o l e , Feed-Through Frame
Mounting Unit
D. Single-Phase, 3- Pole, Feed-Through Box Mounti n g Unit
Note: Choices of ratings or types are shown in
parenthesis.
December 1968
I. Fuses
T h e f u s e s u s e d s h a l l be t h e current-limiting,
non-expulsion type from which no g a s e s a r e rel e a s e d from t h e unit t o t h e surrounding atmosphere during or a f t e r fault interruption. In addition, t h e f u s e s h a l l interrupt fault c u r r e n t s without n o i s e o r mechanical force. T h e f u s e s h a l l
h a v e a n interrupting rating of 50,000 amperes
rms symmetrical o r greater and s h a l l h a v e a current and voltage rating a p p l i c a b l e t o t h e individual installation.
They must b e c a p a b l e of clearing t h e full range
of fault currents from minimum melting through
t h e maximum interrupting rating of t h e f u s e w i t h out t h e a i d of auxiliary d e v i c e s .
F u s e s a r e t o b e of t h e disconnecting t y p e and
must b e completely switch- stick operable, including installation, operation and removal with
distribution c l a s s s w i t c h s t i c k s made i n accordance with NEMA Standard SG2 and USA
Standard C37.42.
E a c h f u s e s h a l l b e equipped with integral loadbreak d e v i c e t o provide full load interruption
when u s e d with t h e stationary contact structure
for which i t i s designed. Operation s h a l l b e
automatic whenever t h e f u s e is opened with a
s w i t c h s t i c k . No auxiliary interrupters, replacea b l e interrupting d e v i c e s or other attachments
s h a l l b e required for proper operation.
T h e construction s h a l l include a s a f e t y feature
which prevents t h e f u s e or s w i t c h from closingin u n l e s s t h e load break is r e s e t and ready for
another operation.
ARC-STRANGLER SWlTCH
Load-Break Disconnect Switch
T h e disconnect s w i t c h e s u s e d s h a l l b e rated
200-ampere full load and 18,000 amperes momentary and h a v e a voltage rating of (8.3 k v or below)
(15 kv).
T h e d i s c o n n e c t s w i t c h must b e completely
switch- stick operable, including installation,
operation and removal, with distribution- class
s w i t c h s t i c k s made in a c c o r d a n c e w i t h NEMA
Page 2
sheltered from direct weather and s h a l l directly
accommodate t h e f u s e s (switches) of the current
and voltage specified.
Standard SG2 and USA Standard C37.42.
Each switch s h a l l be equipped with a n integral
load-break d e v i c e t o provide full load interruption when u s e d with the s t a t i o n a r y contact
structure for which i t i s d esigned. Operation
s h a l l b e automatic whenever this s w i t c h i s opene d with a switch- stick. No auxiliary interrupters,
replaceable interrupting d e v i c e s or other a t t a c h ments s h a l l be required for proper operation.
T h e mounting s h a l l c o n s i s t of a b a s e , s i x insulators and stationary contact a s s e m b l i e s with
appropriate terminals.
T h e b a s e s h a l l c o n s i s t of a s i n g l e formed plate,
approximately 15 i n c h e s wide and adaptable for
wall or structure mounting.
T h e construction s h a l l include a s a f e t y feature
which prevents the f u s e or switch from closingin u n l e s s the load break is r e s e t and ready for
another operation.
Insulators s h a l l b e 95-kv B I L indoor post type,
bolted directly t o the b a s e plate.
MOUNTING AND MOUNTING ARRANGEMENTS
General and Mounting Specifications for SinglePhase Units
T h e f u s e (switch) m o u n t i n g s h a l l be s i n g l e
phase, s i n g l e pole, for u s e in any nonsubmers i b l e location, sheltered from direct weather and
directly accommodate, without modification, t h e
f u s e (switch) of the current and voltage specified.
Insulating barriers s h a l l b e provided between
p h a s e s . T h e s e barriers s h a l l extend beyond the
upper a n d lower e d g e s of the b a s e plate and outward from the live parts t o prevent a c c i d e n t a l
c o n t a c t between a d j a c e n t p h a s e s by s e r v i c e
personnel.
Mountings s h a l l c o n s i s t of a b a s e , two insulators
and stationary contact a s s e m b l i e s with appropriate terminals.
T h e b a s e s h a l l be a formed channel, adaptable
for wall or structure mounting.
Insulators s h a l l be 95-kv BIL indoor post type,
bolted directly t o the b a s e .
Ill-C. General and Mounting Specifications for SinglePhase, 3-Pole Units
Contact a s s e m b l i e s s h a l l accommodate e i t h e r
f u s e s or s w i t c h e s interchangeably and without
modification. T h e lower c o n t a c t s s h a l l be of t h e
hinge d e s i g n t o allow the fuse or switch t o be
retained in a 90° (150° to 1 8 0 ° ) * open position,
yet e a s i l y removed with a standard switch s t i c k
a s described above.
Upper c o n t a c t s s h a l l be of the c l i p type with a
reinforcing backup spring member, and s h a l l b e
s u i t a b l e for u s e with the load-break d e v i c e on
the f u s e or switch. Terminals s h a l l be provided
t o accommodate adequate c a b l e connectors.
Ill-B. General and Mounting Specifications for ThreePhase Units
T h e f u s e (switch) mounting s h a l l be three phase,
3-pole, for u s e in any non-submersible location,
Contact a s s e m b l i e s s h a l l accommodate either
f u s e s or s w i t c h e s interchangeably, without modification. T h e lower c o n t a c t s s h a l l b e of the hinge
design t o allow the fuse or s w i t c h t o b e retained
in a 9 0 ° ( 1 5 0 ° t o 180°)* open p o s i t i o n and
removed with a standard switch s t i c k a s d e s cribed above. Upper c o n t a c t s s h a l l be of t h e
c l i p type with a reinforcing backup s p r i n g member and s h a l l be s u i t a b l e for u s e with t h e loadbreak d e v i c e on t h e f u s e s or s w i t c h e s . Terminals
s h a l l b e provided on e a c h pole t o accommodate
adequate c a b l e connectors.
T h e f u s e and s w i t c h mounting s h a l l be s i n g l e phase, 3 pole, with t h e upper c o n t a c t s commonly
bused. It s h a l l b e s u i t a b l e for u s e in any nonsubmersible location sheltered from direct
weather a n d s h a l l directly accommodate the
the f u s e s and s w i t c h e s of t h e current and voltage
specified.
T h e mounting s h a l l c o n s i s t of a b a s e , five ins u l a t o r s and stationary contact a s s e m b l i e s with
appropriate terminals.
T h e b a s e s h a l l c o n s i s t of a s i n g l e formed plate
approximately 1 5 i n c h e s wide, adaptable for wall
or structure mounting.
Insulators s h a l l be 95-kv BIL indoor post type
bolted directly t o the b a s e .
Page 3
Contact assemblies s h a l l accommodate either
fuses or switches interchangeably and without
modification. The lower contacts shall be of a
hinge design to allow the fuse or switch to be
retained in a 90° (150° to 180°)* open position,
yet easily removed with a standard switch-stick
a s described above. Upper contacts s h a l l be of
the clip type with a reinforcing backup spring
member and s h a l l be suitable for u s e with the
load-break device on the fuse and switches. The
upper contact poles shall be commonly bused
and supported on two insulators. Terminals s h a l l
be provided on the lower contacts to accommodate adequate cable connectors.
Insulating barriers s h a l l be provided between
poles. These barriers s h a l l extend upward sufficiently to properly insulate the lower contacts
one from the other, downward beyond the lower
edges of the base plate, and outward from the
live parts to prevent accidental contact between
adjacent phases by service personnel.
Ill-D. General and Mounting Specifications for Sin g le Phase, 3 - Pole, Molded Box Mounted Unit
The fuse and switch mounting s h a l l be single
phase, 3-pole, with the upper contacts commonly
bused. It s h a l l be suitable for use in any nonsubmersible location sheltered from direct weather and shall directly accommodate, without
modification, fuses and switches up through 8.3
kv of the current specified.
The mountings s h a l l consist of a single, molded
box of fiber-glass reinforced polyester with
non-tracking additives, stationary contact a s semblies, and appropriate terminals. The onepiece box s h a l l perform the functions of base,
insulators, and barriers. The mounting box shall
be approximately 9 inches wide, 20 inches high,
and 10 inches deep a t the deepest point. A portion of the box shall form a thru-bushing for
connecting the lower middle contact directly
through the wall of an oil-filled compartment.
Impulse insulation strength s h a l l be not l e s s
than 75-kv BIL when mounted directly to the
oil-filled compartment wall with ground plane
sidewalls a minimum of 1-1/8 inches from the s i d e s
of the box. Minimum creepage distances over the
s u r f a c e o f the box from any live part to any
ground part shall be not l e s s than 19 inches.
Contact assemblies shall mount directly to metal
inserts molded in the box and shall accommodate
either fuses or switches interchangeably and
without modification. The lower contacts shall
be of the hinge design to allow the fuse or the
switch to be retained in a 90° open position,
yet easily removed with a standard switch stick
a s described above. Each contact of the upper
contact assembly shall be of the c l i p type with
a reinforcing backup spring member and shall
be suitable for use with the load-break device
on the fuse or switch. The three upper contact
clips shall be bused in a common assembly.
Terminals s h a l l be provided on the two outside,
lower contact assemblies to accommodate adequate cable connectors.
* N o t e : 150° to 180° opening recommended i f
lower contact i s higher than 4-1/2 feet off
the ground.
1045 Hickory Street
Pewaukee, Wisconsin USA
www.cooperpower.com
© 1968 Cooper Power Systems or its affiliates
NX is a registered trademark of Cooper Power Systems or its affiliates