MindCore
expulsion power fuse
7.5 kV. to 69 kV.
100 to 400 Amp
epf
FEATURES
•
•
•
•
•
•
DESCRIPTION
Fuse element included at no extra charge.
Fuse holder ‘drops out’ for easy identification
of blown fuse.
Meets or exceeds ‘NEMA’ requirements
Copper alloy current carrying parts.
Reverse loop jaw contacts with positive
latching.
Self locking hinge.
DESCRIPTION
1845 Jean-Monnet, Terrebonne QC J6X 4L7
The MindCore Technologies “EPF” is a heavy duty
power fuse offered in voltage ratings from 7.5 kV through
69 kV, in continuous ratings of 100 and 400 amperes,
and interrupting capacities as high as 3,608,200 kVA
symmetrical at 69 kV. It is available in vertical, horizontal, underhung, and 45º underhung mounting positions.
A variety of type EPF fuse holders are available in both
100 and 400 ampere continuous current ratings. The
desired fuse holder should be selected on the basis of
interrupting capacity required and the continuous current rating of the maximum size fuse link assembly to
be used.
TEL.: 450.477.5959 FAX: 450-477.2220 www.mindcoretech.com
MindCore
expulsion power fuse
7.5 kV. to 69 kV.
100 to 400 Amp
epf
APPLICATION
High-voltage power fuses provide short-circuit protection for equipment and systems in installations where a
circuit breaker is economically prohibitive. Power fuses
provide consistent and fast short-circuit protection.
They do not provide automatic restoration of service,
and it is not advisable to use them in locations where
the frequency of operation is likely to be great. The
principal application of power fuses is for the primary
or secondary protection of power transformers. Power
fuses can also be used on feeder circuits and capacitor
banks.
for subsequent refusing, is a fraction of the cost associated with fuse units and refill units utilized by competitive fuses of comparable performance.
SELECTION
The following factors should be considered in the
selection of a power fuse:
Voltage Rating – Select a fuse having a maximum
design voltage rating equal to or greater than the system line to line voltage.
Interrupting Rating – Determine the maximum
PERFORMANCE
The power fuses described in this bulletin are designed
to perform in accordance with NEMA standards. Essentially, these performance or testing standards
require that:
asymmetrical short-circuit current available on the
system at the fuse location. Select a fuse having an
interrupting capacity equal to or greater than the
available short-circuit current.
1. The power fuse, when fused with the maximum rated fuse link assembly, shall carry the
rated current of the fuse link assembly with a
temperature rise not exceeding 30 ºC above
an ambient within the range of 10ºC to 40ºC.
2. The power fuse shall interrupt currents
of any magnitude from the minimum current
required to melt the current responsive element to the interrupting rating of the fuse.
The MindCore Technologies type EPF power fuse
is a modern, reliable protective device – the result of
over 50 years’ experience in power fuse design and
development.
Ratings
Recommended Clearance Dimensions
kV.
Dim. X
Dim. Y
Minimum
Phase to
Phase
spacing
Nom.
Max.
BIL.
Inches (mm)
Inches (mm)
Inches (mm)
7.5
8.25
95
40 (1016)
44 (1118)
36 (914)
15
15.5
110
47 (1194)
46 (1168)
36 (914)
23
25.8
150
56 (1422)
48 (1219)
48 (1219)
34.5
38
200
66 (1676)
51 (1295)
60 (1524)
46
48.3
250
78 (1981)
54 (1372)
72 (1828)
69
72.5
350
106 (2692)
65 (1651)
84 (2134)
This series of power fuses offers the maximum in reliability, ease of operation, and economy. Reliability is
assured by the dual operating characteristics of the
expendable cap design and the “arc quenching” fuse
element construction. Ease of operation results from
the full drop-out action of the fuse holder and the provisions for handling all ratings with a hookstick. Economy
is significant both at the time of the original installation
and at the time of refusing. The cost of a fuse element
1845 Jean-Monnet, Terrebonne QC J6X 4L7
TEL.: 450.477.5959 FAX: 450-477.2220 www.mindcoretech.com
MindCore
expulsion power fuse
7.5 kV. to 69 kV.
100 to 400 Amp
epf
RECOMMENDED MOUNTING CLEARANCE
One of the significant advantages associated with the
EPF power fuses is the low cost of restoring these units
to service after an operation. A special fuse kit, makes
them easy and inexpensive to refuse. The kit consists
of an expendable cap, fuse link assembly and disposable re-fusing tool. No other parts are required.
The fuse kits are available in four speed ratios: PF (slow
speed), PM (medium speed), PX (fast speed) and the
EEI-NEMA type PE. Time current characteristic curves
are available upon request.
It is recommended that links be applied in fuse holders
in accordance with the coordination table below.
Link Rating
Amperes
Fuse Holder Rating
Amperes
1 to 100
100
125 to 200
200
250 to 300
300
350 to 400
400
1845 Jean-Monnet, Terrebonne QC J6X 4L7
TEL.: 450.477.5959 FAX: 450-477.2220 www.mindcoretech.com
MindCore
expulsion power fuse
7.5 kV. to 69 kV.
100 to 400 Amp
epf
AVAILABLE MOUNTING ARRANGEMENTS
1845 Jean-Monnet, Terrebonne QC J6X 4L7
TEL.: 450.477.5959 FAX: 450-477.2220 www.mindcoretech.com
MindCore
expulsion power fuse
7.5 kV. to 69 kV.
100 to 400 Amp
epf
Amperes
kV.
Interrupting capacity
Cont.
Nom. Max. BIL.
100
7.5
15
8.25
15.5
95
110
200
300
400
100
34.5
25.8
38
150
200
48.3
250
350
35
272,200
25
35
25
521,000
583,200
521,000
35
100
25
35
25
1,117,800
1,490,400
1,117,800
35
1,490,400
25
35
25
1,490,400
1,987,200
1,490,400
35
1,987,200
25
35
25
1,863,000
2,608,200
1,863,000
35
2,608,200
200
300
400
Weight
EPF071B
EPF071H
EPF072B
EPF072H
EPF073H
EPF074H
EPF151B
EPF151H
EPF152B
EPF152H
EPF153H
48 (22)
69 (31)
48 (22)
69 (31)
59 (27)
80 (36)
59 (27)
80 (36)
EPF154H
993,600
200
202
583,200
35
200
300
400
Catalog Number
Vertical***
mounting only
(Fig.V)
Lbs. (kg.)
205
200
300
400
100
72.5
194,400
272,200
194,400
745,200
993,600
745,200
300
400
69
25
35
25
25
35
25
100
46
kVA.** 3 Phase
Sym.
200
300
400
100
23
RMS* Asym.
kA.
Insulator T.R.
No.
1845 Jean-Monnet, Terrebonne QC J6X 4L7
208
210
214
216
EPF231B
EPF231H
EPF232B
EPF232H
EPF233H
EPF234H
EPF341B
EPF341H
EPF342B
EPF342H
EPF343H
EPF344H
EPF461B
EPF461H
EPF462B
EPF462H
EPF463H
EPF464H
EPF691B
EPF691H
EPF692B
EPF692H
EPF693H
EPF694H
88 (40)
101 (46)
88 (40)
101 (46)
111 (50)
136 (62)
111 (50)
136 (62)
156 (71)
171 (78)
156 (71)
171 (78)
240 (109)
279 (127)
240 (109)
279 (127)
TEL.: 450.477.5959 FAX: 450-477.2220 www.mindcoretech.com
MindCore
expulsion power fuse
7.5 kV. to 69 kV.
100 to 400 Amp
epf
1. Fuse elements are included with a power fuse assembly. Please advise the amperage and the speed of the
fuse elements required when placing an order (please refer to the following pages for full details on MindCore
Technologies fuse elements).
2. Power fuse standardized bases will be provided as detailed, unless otherwise requested at time of
ordering.
3. For replacement fuse holder only, which includes the fuse tube and both the hinge contact and the
male jaw contact, insert the letter H as the forth character of the catalog number. eg…EPFH071B.
Dimensions
Voltage kV. Nom.
Interrupting
Capacity, RMS
Asym. kA.
7.5
25
15
35
30
23
37.5
30
34.5
40
30
69
46
40
30
40
25
40
Inches
13
15
20
24
30
36
39
Dim. A
mm.
330
381
508
610
762
914
991
Inches
19
21
26
30
36
42
45
mm.
483
533
660
762
914
1067
Inches
7.5
10
14
18
22
Dim. B
1143
30
Dim. C
mm.
191
254
457
356
559
762
Inches
10
10.12
12.5
12.62
16.5
16.62
20.5
20.62
23.5
23.62
34.25
34.31
mm.
254
257
318
321
419
422
521
524
597
600
870
873
Dim. D
Inches
17
19
22
28
34
37
40
mm.
432
483
559
711
864
940
1016
Dim. E
Inches
38.12
38.87
43.75
44.5
50.25
51
62.62
63.37
75
75.75
96.87
97.62
mm.
968
987
1111
1130
1276
1295
1581
1610
1905
1924
2461
2480
Inches
31.62
32.5
36.12
37
41.12
42
50.12
51
59.25
60.12
77
77.87
mm.
803
826
917
940
1045
1067
1273
1295
1505
1527
1956
1978
Dim. F
Dim. G
1845 Jean-Monnet, Terrebonne QC J6X 4L7
TEL.: 450.477.5959 FAX: 450-477.2220 www.mindcoretech.com
MindCore
expulsion power fuse
7.5 kV. to 69 kV.
100 to 400 Amp
epf
OPERATION
MindCore Technologies fuse elements are capable
of handling a full range of fault currents. Faults just
high enough to melt the fusible element, or those up to
the assigned interrupting rating of the unit are handled
with equal ease.
faults, or when pressures are sufficient to quench the
arc, the disc is expelled.
The cap, in addition to providing a highly successful
means for confining gases, serves to seal the top of
the fuse holder, preventing the entrance of moisture
into the tube bore.
THE PROBLEM
In the past the most critical zone of operation for a fuse
has been on restricted faults. The conventional fuse
was occasionally incapable of generating a sufficient
volume of gas to quench the arc. The problem on such
faults was aggravated by the open bore tube which offered little restriction for gas confinement. Conditions
suitable for quick circuit interruption were not present.
As a consequence the performance characteristics at
low values of fault current were not dependable.
THE APPROACH
MindCore Technologies approached the problem
with two objectives:
Provide a means for confining gasses on low current
faults without sacrificing interrupting capacity.
Provide an additional source for gas that would be developed by arc heat during the initial stages of a low
current fault.
THE EXPENDABLE CAP
The expendable cap proved to be the answer to the
first problem. It provides a simple means for confining
gasses, yet it allows completely free venting on high
current faults.
HOW DOES IT WORK?
The cap is constructed in two parts (1) the threaded
ring which screws in position at the top of the fuse
holder and (2) a small disc, built into the ring, which is
positioned directly over the tube bore when the cap is
installed.
On low current faults, the disc stays in position allowing
pressures to build to suitable levels. On high current
1845 Jean-Monnet, Terrebonne QC J6X 4L7
TEL.: 450.477.5959 FAX: 450-477.2220 www.mindcoretech.com
MindCore
expulsion power fuse
7.5 kV. to 69 kV.
100 to 400 Amp
epf
THE BORIC ACID FUSE ELEMENT
The boric acid fuse element is the answer to the
second problem. It provides a source for the development of a large volume of gas even where
values of fault current are extremely low.
HOW DOES IT WORK?
The fusible element, encased in a strong auxiliary
tube, is buried in a mass of boric powder. When
exposed to the heat of an arc, the boric acid gives
up most of its weight as water. Conversion of water
to steam, in addition to providing a large volume
of gas, aids in cooling the arc. The steam, as it
moves through the arc stream, purges it of ionized
gas.
LOW CURRENT FAULT OPERATION
The illustrations at right demonstrate the function
of the holder and link assembly in clearing a restricted fault.
In the first illustration the fusible element has melted
and the lower section of link is being ejected.
An arc is established directly in the mass of boric
acid powder converting it to water and then to
steam. Gas pressure, confined by the expandable
cap, and the relatively long column of air in the lower
tube, mounts rapidly. Interruption of the arc is swift
and sure.
During the critical initial stages of a low current
fault, the ejector spring performs a dual task. It
serves to snap the lower section of the link out
of the tube bore as soon as the element melts. At
the same time, it holds the sealing disc against the
counter bored shoulder of the fuse tube. The disc
serves to provide a partial gas seal aiding in arc
extinction.
The ejector spring is compressed when the fuse
element assembly is installed.
1845 Jean-Monnet, Terrebonne QC J6X 4L7
TEL.: 450.477.5959 FAX: 450-477.2220 www.mindcoretech.com
MindCore
expulsion power fuse
7.5 kV. to 69 kV.
100 to 400 Amp
epf
HIGH CURRENT FAULT OPERATION
The problems encountered on high current faults
are exactly opposite those of low current fault operations. On high current faults a large volume of
gas is generated. The function of the holder, instead of confining gas, is to provide an efficient
means for dissipating the great gas pressures
present.
Further, it must handle the forces associated with
such an operation, without transmitting damaging
shock to the fuse mounting.
To do this, it is necessary to vent the fuse tube
at both ends. Gas must be quickly relieved and
the “rocket effect” associated with a single vented
fuse must be eliminated.
The expendable cap is the answer. The disc in
the cap is expelled instantly and the tube is free
to vent at both ends. The forces of expulsion are
balanced and the mounting and holder are undamaged.
The sealing disc at the bottom of the tube assumes a new role on high current faults. When
high gas pressure impinges on its upper surface,
the disc becomes a small piston driving downward. As shown in the illustration, inertia of the
cable causes the spring to be compressed by the
fast moving disc. Action of the disc is to propel
the remainder of link clear of the tube bore.
1845 Jean-Monnet, Terrebonne QC J6X 4L7
TEL.: 450.477.5959 FAX: 450-477.2220 www.mindcoretech.com
MindCore
expulsion power fuse
7.5 kV. to 69 kV.
100 to 400 Amp
epf
FUSE ELEMENT CURRENT RATING
FUSE ELEMENT CHARACTERISTIC
The current rating of a fuse element must be sufficiently large to handle normal short-time overloads
and energizing and switching surges under normal
The NEMA Standard “E” rating – An “E” rated
operating conditions without blowing. The current
fuse element 100 amperes and below will melt in
rating of the fuse element recommended for vari300 seconds at a current within the range of 200
ous size transformers is tabulated in the following
to 240 per cent of the continuous current rating.
tables and takes into account these factors:
Fuse elements above 100 amperes will melt in
a. Short-time daily overloads within the limits
600 seconds at a current within the range or 220
recommended by the ASA Publication, “Guide
to 264 per cent of the continuous current rating.
for Overloading Oil Immersed Distribution and
The “N” rating – An “N” rated fuse element will
Power Transformers”, Appendix C57.92 dated
melt in 300 or 600 seconds at a current within the
January, 1956.
range of 69 to 125 per cent of the continuous curb. Transformer magnetizing inrush current up
rent rating.
to 12 times the transformer full load current for
Power fuse elements are available in four speed
0.1 second.
ratios to provide the best possible coordination.
c. Switching surges normally experienced
on a utility system.
MindCore Technologies power fuse elements
are available on two bases of rating:
Link Rating
Amperes
Fuse Holder Rating
Amperes
1 to 100
100
125 to 200
200
250 to 300
300
350 to 400
400
d.
Ambient temperature up to 40ºC.
Where coordination with other protective devices
is not of primary importance, the type “PE” fuse
unit is recommended.
CO-ORDINATION
Coordination is based on the principle that the
protective device nearest short circuit or overload will operate, thus isolating a minimum portion of the system.
a. For general application, the fuse unit
selected from the following chart will provide
adequate coordination with usual primary and
secondary protective devices.
a. If closer coordination is required please
refer to detailed time-current characteristic
curves which are available upon request.
1845 Jean-Monnet, Terrebonne QC J6X 4L7
TEL.: 450.477.5959 FAX: 450-477.2220 www.mindcoretech.com
MindCore
expulsion power fuse
7.5 kV. to 69 kV.
100 to 400 Amp
epf
Single Phase Distribution Transfromers Fuse Element Ratings
System kV.
13.8
Fuse kV.
15
Full
Transforme
Load
r kVA.
Curre
Rating
nt
22
33
23
"E"
"N"
Full
Load
Curre
nt
Fuse Rating
44
34.5
"E"
"N"
Full
Load
Curre
nt
Fuse Rating
66
46
"E"
"N"
Full
Load
Curre
nt
Fuse Rating
69
"E"
"N"
Full
Load
Curre
nt
Fuse Rating
Fuse Rating
"E"
"N"
25
1.8
3
5
1.14
3
3
0.76
3
3
-
-
-
-
-
-
50
3.6
5
8
2.3
5
5
1.5
3
3
1.13
3
3
-
-
-
100
7.2
10
15
4.5
7
10
3
5
8
2.3
5
5
1.5
3
3
167
12
20
25
7.6
10
15
5.1
7
12.5
3.8
5
8
2.5
5
5
333
24
40
50
15
20
30
10
15
20
7.6
10
15
5
7
10
500
36
50
75
23
30
50
15
20
30
11
15
25
7.5
10
15
Three Phase Power & Distribution Transformers
Fuse Element Ratings
System kV.
13.8
22
33
44
Fuse kV.
15
23
34.5
46
Transform
Full Load
er kVA.
Current
Rating
Fuse Rating
"E"
"N"
Full Load
Current
Fuse Rating
"E"
"N"
5
5
Full Load
Current
Fuse Rating
"E"
"N"
1.3
3
3
Full Load
Current
Fuse Rating
"E"
"N"
1
3
3
75
3.2
5
8
2
150
6.3
10
12.5
3.9
7
8
2.6
5
8
2
5
5
225
9.4
15
20
5.9
10
12.5
3.9
7
10
2.9
5
8
300
12.5
20
25
7.9
15
20
5.3
10
12.5
4
7
10
500
21
30
40
13.1
20
30
8.8
15
20
6.6
10
15
750
31.5
50
75
20
30
40
13.1
20
30
9.9
15
20
1000
42
65
100
26.5
40
60
17.5
25
40
13.1
20
30
1500
63
100
125
39
65
100
26
40
60
19.7
30
40
2000
84
125
200
52
80
125
35
65
75
26
40
60
2500
104
150
250
66
100
150
44
65
100
33
50
75
3750
157
-
300
98
150
200
66
100
150
49
80
100
5000
208
-
400
131
200
300
88
125
200
66
100
150
7500
-
-
-
197
-
400
131
200
300
99
150
200
10000
-
-
-
-
-
-
176
-
350
131
200
300
15000
1845 Jean-Monnet, Terrebonne QC J6X 4L7
198
400
TEL.: 450.477.5959 FAX: 450-477.2220 www.mindcoretech.com
MindCore
expulsion power fuse
7.5 kV. to 69 kV.
100 to 400 Amp
epf
APPLICATION IN TYPES EPF POWER FUSE ELEMENTS
The fuse elements tabulated below were specifically designed for use in MindCore Technologies type
EPF power fuses. No other type of elements are suitable for use in these power fuses.
Four speed ratios, indicated by the prefixes PF, PM, PX or PE are available as shown below.
It is important to observe the recommended element holder combination listed on page 6.
When ordering elements, the complete catalogue number consists of the characteristic, followed by
the voltage and then the current rating. For example, a fuse with a PF characteristic rated 69 kV and
75 A would be catalogue number PF69075.
Fuse Elements for Fuses Rated 7.2 kV. To 7.2 kV. To 69 kV.
Fuse Element Types Available in Ampere
Ratings Shown
Catalog Code Numbers
PF
PM
PX
PE
7.5 kV.
15 kV.
23 kV.
34.5 kV.
46 kV.
69 kV.
1
2
3
5
8
10
12.5
15
20
25
30
40
50
60
75
100
125
150
200
250
300
-
2
3
5
8
10
12.5
15
20
25
30
40
50
60
75
100
125
150
200
250
300
350
400
3
5
8
10
12.5
15
20
25
30
40
50
60
75
100
125
150
200
250
300
-
1
2
3
5
7
10
15
20
25
30
40
50
65
80
100
125
150
200
-
75001
75002
75003
75005
75007
75008
75010
75012.5
75015
75020
75025
75030
75040
75050
75060
75065
75075
75080
75100
75125
75150
75200
75250
75300
75350
75400
15001
15002
15003
15005
15007
15008
15010
15012.5
15015
15020
15025
15030
15040
15050
15060
15065
15075
15080
15100
15125
15150
15200
15250
15300
15350
15400
23001
23002
23003
23005
23007
23008
23010
23012.5
23015
23020
23025
23030
23040
23050
23060
23065
23075
23080
23100
23125
23150
23200
23250
23300
23350
23400
34001
34002
34003
34005
34007
34008
34010
34012.5
34015
34020
34025
34030
34040
34050
34060
34065
34075
34080
34100
34125
34150
34200
34250
34300
34350
34400
46001
46002
46003
46005
46007
46008
46010
46012.5
46015
46020
46025
46030
46040
46050
46060
46065
46075
46080
46100
46125
46150
46200
46250
46300
46350
46400
69001
69002
69003
69005
69007
69008
69010
69012.5
69015
69020
69025
69030
69040
69050
69060
69065
69075
69080
69100
69125
69150
69200
69250
69300
69350
69400
1845 Jean-Monnet, Terrebonne QC J6X 4L7
TEL.: 450.477.5959 FAX: 450-477.2220 www.mindcoretech.com