HTFX320200 - Hi-Tech Fuses

January 2001 • Supersedes June 1997 • 2001 Hi-Tech Fuses, Inc. 1

General:

The Trans-Guard FX full-range current-limiting fuse provides both

overload and fault current protection for distribution equipment in a

single fuse body. As a full-range fuse, it is capable of interrupting any

continuous current between the minimum current that can cause

melting of its elements and its rated maximum interrupting current

(50,000 amps). The fuses are capable of interrupting in elevated

ambient temperatures up to their rated maximum application

temperature, which is 140° C and 71° C for the 2.2 inch and 3.3 inch

diameter designs, respectively. The Trans-Guard FX fuse is

hermetically sealed and thus discharges no gasses during fuse

operation. An additional design distinction is its patented Damage

Sensor that significantly reduces the potential for fuse failure in the

event of element damaging current surges.

Applications:

Trans-Guard FX fuses are available in a broad range of ratings. For ease of application, all designs are

compatible with the industry-recognized standard mounting codes. Common applications include the

Trans-Guard FX:

q installed in dry-well canisters for distribution

transformer protection (see Figure 1)

q clip mounted in live-front switchgear (see Figure 2)

q externally mounted on overhead distribution

systems (outdoor version)

q encapsulated in rubber housings for installation in

underground vaults

q installed in “wet-well” fuseholders for oil-filled

padmounted switchgear (special “SFX” version)

Design Features:

Ø Patented Damage Sensor designed to significantly reduce the risk of fuse failure should the

fuse be subjected to an element damaging current surge.

Ø Hermetically sealed construction ensures that no gasses escape from the fuse during current

interruption. All Trans-Guard FX fuses are helium mass spectrometer leak tested to ensure sealing

system integrity.

Ø Optional blown fuse indicator provides reliable indication of fuse operation without adversely

affecting the fuse’s arcing performance due to its unique design.

Ø Versatile design – With its hermetically sealed construction and resin-rich body surface, the

same fuse can be used for both in-air and under-oil applications.

Ø Rugged cast bronze end caps used for greater ferrule strength resulting in less distortion and

more secure fuse attachment in dry-well canisters.

Ø Tested in accordance with the most recent ANSI/IEEE standards, which include requirements

for short circuit testing at the manufacturer’s specified rated maximum application temperature

(140° C and 71° C for 2.2 inch and 3.3 inch diameter Trans-Guard FX designs, respectively).

Trans-Guard FX

Full-Range Current-Limiting Fuse Line

Trans-Guard FX Full-Range Current-Limiting Fuses

K

H

T

F

u

s

e

s

,

L

C

Figure 1 Figure 2

A Hi-Tech Fuses Company

January 2001 • Supersedes June 1997 • 2001 Hi-Tech Fuses, Inc. 2

Dimensions inches (mm)

Voltage

(kV) Current

(amp) A B C

Standard

Mounting

Code

5.5 80-200 17.51-

17.35

(444.8-440.7)

1.21-

1.17

(30.7-29.7) 3.32-

3.25

(84.4-82.5) 6

3-50 10.00-

9.86

(254.0-250.4)

1.02-

.98

(25.9-24.9) 2.25-

2.18

(57.0-55.3) 4

8.3 65-125 14.7-

14.54

(373.4-369.3)

1.21-

1.17

(30.7-29.7) 3.32-

3.25

(84.4-82.5) 5

3-50 14.31-

14.17

(363.5-359.9)

1.02-

.98

(25.9-24.9) 2.25-

2.18

(57.0-55.3) 5

15.5 65-100 17.51-

17.35

(444.8-440.7)

1.21-

1.17

(30.7-29.7) 3.32-

3.25

(84.4-82.5) 6

23.0 6-50 17.12-

16.98

(434.8-431.3)

1.02-

.98

(25.9-24.9) 2.25-

2.18

(57.0-55.3) 6

Construction:

Table 1 - Trans-Guard FX Fuse Dimensional Information

Trans-Guard FX Full-Range Current-Limiting Fuses

Tin plated

bronze caps

Resin-rich filament wound

glass/epoxy body

Mica element

support High current

interruption element

Low current interruption

element (includes patented

damage sensor)

Compacted

quartz sand

Soldered electrical

connection and sealing

Optiona

l blown

fuse indicator

Welded element

joints Epoxy

Joint

0.625

(15.9)

“B”

“C”

Length “A”

January 2001 • Supersedes June 1997 • 2001 Hi-Tech Fuses, Inc. 3

Electrical Characteristics:

Table 2a - Electrical Characteristics of Trans-Guard FX Fuses (Single Fuses)

NOMINAL

VOLTAGE

RATING

CURRENT

RATING FUSE

MODEL

NUMBER

RATED

MAXIMUM

VOLTAGE

MAXIMUM CONTINUOUS

CURRENT (IN AIR)

(6)

PEAK ARC

VOLTAGE

(kV) MINIMUM

MELT I2t

MAXIMUM

TOTAL I2t

(3) (4)

(kV) (A) (kV) 25O C 40O C 55O C (5) (AMP2 SEC) (AMP2 SEC)

5.5 80 HTFX320080 5.5 99 96 94 15.0 22,100

110,000

5.5 100 HTFX320100 5.5 126 122 118 15.0 56,700

280,000

5.5 125 HTFX320125 5.5 142 138 134 15.0 78,300

380,000

5.5 150 HTFX320150 5.5 184 178 173 15.0 176,000

860,000

5.5 200 HTFX320200 5.5 208 202 196 15.0 259,000

1,270,000

8.3 3 HTFX230003

10.0 5.0 4.9 4.7 30 100

350

8.3 6 HTFX230006

10.0 11.0 10.5 10.0 32 620

2,700

8.3 8 HTFX230008

10.0 13.5 13.0 12.5 28 800

4,000

8.3 10 HTFX230010

10.0 16.0 15.5 15.0 28 800

4,000

8.3 12 HTFX230012

10.0 20.5 19.5 19.0 26 920

8,000

8.3 18 HTFX230018

10.0 23.5 22.5 22.0 26 1,310

9,500

8.3 20 HTFX230020

10.0 27.5 26.5 25.5 26 1,620

11,000

8.3 25 HTFX230025

10.0 37.0 35.5 34.5 26 3,660

22,000

8.3 30 HTFX230030

10.0 41.0 39.5 38.5 26 5,250

30,000

8.3 40 HTFX230040

10.0 50.0 48.5 47.0 26 8,700

50,000

8.3 50 HTFX230050

10.0 57.0 55.0 53.5 26 12,800

70,000

8.3 65 HTFX330065

8.3 81.0 79.0 77.0 25 25,200

100,000

8.3 80 HTFX330080

8.3 95.0 92.0 89.0 25 47,200

185,000

8.3 100 HTFX330100

8.3 120.0 117.0 113.0 25 78,300

330,000

8.3 125 HTFX330125 8.3 135.0 131.0 127.0 25 115,150

480,000

15.5 3 HTFX240003

17.2 5.0 4.9 4.7 51 100

510

15.5 6 HTFX240006

17.2 11.0 10.5 10.0 54 620

2,600

15.5 8 HTFX240008

17.2 13.5 13.0 12.5 46 800

3,700

15.5 10 HTFX240010

17.2 16.0 15.5 15.0 46 800

3,700

15.5 12 HTFX240012

17.2 20.5 19.5 19.0 43 920

6,500

15.5 18 HTFX240018

17.2 23.5 22.5 22.0 45 1,310

8,000

15.5 20 HTFX240020

17.2 27.5 26.5 25.5 45 1,620

10,000

15.5 25 HTFX240025

17.2 37.0 35.5 34.5 45 3,660

22,000

15.5 30 HTFX240030

17.2 41.0 39.5 38.5 45 5,250

30,000

15.5 40 HTFX240040

17.2 50.0 48.5 47.0 45 8,700

50,000

15.5 50 HTFX240050

17.2 53.0 51.5 50.0 45 12,800

70,000

15.5 65 HTFX340065

15.5 78.0 75.0 73.0 40 25,200

110,000

15.5 80 HTFX340080

15.5 88.0 85.0 82.0 40 39,400

185,000

15.5 100 HTFX340100

15.5 114.0 110.0 107.0 40 80,000

380,000

23.0 6 HTFX250006

23.0 11.0 10.5 10.0 67 620

3,100

23.0 8 HTFX250008

23.0 13.5 13.0 12.5 61 800

4,800

23.0 10 HTFX250010

23.0 16.0 15.5 15.0 61 800

4,800

23.0 12 HTFX250012

23.0 20.5 19.5 19.0 60 920

8,300

23.0 18 HTFX250018

23.0 23.5 22.5 22.0 60 1,310

11,200

23.0 20 HTFX250020

23.0 27.5 26.5 25.5 60 1,620

13,000

23.0 25 HTFX250025

23.0 37.0 35.5 34.5 60 3,660

28,000

23.0 30 HTFX250030

23.0 41.0 39.5 38.5 60 5,250

38,000

23.0 40 HTFX250040

23.0 48.0 46.5 45.0 60 8,700

61,000

23.0 50 HTFX250050

23.0 55.0 53.0 51.5 60 12,800

82,000

Trans-Guard FX Full-Range Current-Limiting Fuses

January 2001 • Supersedes June 1997 • 2001 Hi-Tech Fuses, Inc. 4

Table 2b - Electrical Characteristics of Trans-Guard FX Fuses (Parallel Fuses)

NOMINAL

VOLTAGE

RATING

CURRENT

RATING

(A)

FUSE

MODEL NUMBER

(Order Two fuses)

RATED

MAXIMUM

VOLTAGE

MAXIMUM CONTINUOUS

CURRENT (IN AIR)

(6)

PEAK ARC

VOLTAGE

(kV)

MINIMUM

MELT I2t MAXIMUM

TOTAL I2t

(3) (4)

(kV) (2) (kV) 25O C 40O C 55O C (5) (AMP2 SEC) (AMP2 SEC)

8.3 60 HTFX230030 10.0 80.0 77.0 75.0 26 21,000

120,000

8.3 80 HTFX230040 10.0 98.0 95.0 92.0 26 34,000

180,000

8.3 100 HTFX230050 8.3

111.0

108.0

105.0 24 51,200

250,000

8.3 130 HTFX330065 8.3 158.0 154.0 151.0 24 100,800

400,000

8.3 160 HTFX330080 8.3 186.0 180.0 175.0 24 189,000

740,000

8.3 200 HTFX330100 8.3 235.0 229.0 221.0 24 313,000

1,300,000

8.3 250 HTFX330125 8.3 265.0 256.0 249.0 24 460,500

1,800,000

15.5 60 HTFX240030 17.2 80.0 77.0 75.0 45 21,000

110,000

15.5 80 HTFX240040 17.2 98.0 95.0 92.0 45 34,800

170,000

15.5 100 HTFX240050 17.2 104.0 101.0 98.0 45 51,200

310,000

15.5 130 HTFX340065 15.5 152.0 147.0 143.0 39 100,800

440,000

15.5 160 HTFX340080 15.5 172.0 167.0 160.0 39 157,500

740,000

15.5 200 HTFX340100 15.5 222.0 214.0 208.0 39 320,000

1,520,000

Notes to Table 2a and 2b:

1. Designs have a 50,000 Amps rms. Symmetrical Rating (except 3A 17.2 kV which was tested at 44 kA maximum).

2. Current ratings shown in Table 2b are achieved by using a parallel combination of two fuses (order two fuses).

To facilitate equal sharing of the interrupting duty, the two fuses should be resistance matched (± 2%) and be

mounted such that the current paths to and from each fuse are symmetrical.

3. Tabulated Maximum Total I2t values are for currents of 50,000 amperes at the nominal voltage of the fuse.

Fuses that have a Rated Maximum Voltage higher than their Nominal Voltage Rating will have a higher I2t let-

through when applied at voltages up to these higher values. For example, Maximum Total I2t values are

increased by approximately 30% when 8.3 kV fuses are applied at 10 kV and approximately 25% when 15.5 kV

fuses are used at 17.2 kV.

4. Maximum total I2t values are reduced for currents below 50,000 A. For example, at 10,000 A, maximum total I2t

values are approximately 15% less than the published values.

5. Peak arc voltages quoted are for 50,000 A currents at the rated maximum voltage listed. Reduced currents and

voltages will reduce the peak arc voltage. Consult the factory for further information.

6. Maximum continuous currents at higher ambient temperatures, and in confining enclosures:

• These may be determined by derating the fuses by 0.2% per degree C over 25O C (for example at 85O C the

derating would be 60 x .2 = 12%, making the maximum continuous current of a 30 A fuse 41 x .88 = 36.1 A).

• When fuses are applied in a confining enclosure, such as a dry-well canister, additional derating of a fuse’s

maximum continuous current is necessary. Specifically, the maximum continuous current for fuses used in a

dry-well canister, with the canister completely submerged in oil, will be reduced by an additional 2%. When

calculating the derating for temperature, as described above, the temperature of the oil surrounding the

canister should be used. For other types of enclosures, please consult the factory.

7. Reduction in the long time melting current of the fuses (approximately one hour and longer) due to higher

ambient temperatures and use in enclosures is the same as described above for "maximum continuous currents".

See time-current characteristics for melting characteristics in this time region.

Trans-Guard FX Full-Range Current-Limiting Fuses

January 2001 • Supersedes June 1997 • 2001 Hi-Tech Fuses, Inc. 5

Application Tables:

Table 3 - Recommended Trans-Guard FX Mounted in a Dry Well Canister in Oil

(Maximum Oil Temperature of 100°° C)

Recommended Fuse Current Ratings (Amperes)

Fuse Voltage 8.3 kV 15.5 kV 23 kV

Transformer 1-Phase Voltage Rating (kV) Phase-to-Ground

2.4 4.16 4.8 7.2 7.62 12 14.4 16 19.9

1-Phase

Transformer

kVA A B A B A B A B A B A B A B A B A B

10 6b 8 6a 3 3a 3a 3a 3a 3a 6a

15 8 12 6 6 3 3 3a 3a 3a 6a

25 18 25 8 12 8b 10 6 6 3 3 3 6a

37.5 20 40 12 20 12b 20 8 10 8b 10 6 6a 6a 6a

50 30 50 18 30 18 25 10 18 10 12 6b 8 6 6 6a

75 50 80 25 40 25 40 18 25 18 20 8 12 8 10 8b 10 6b 8

100 60 100 40 50 40 50 20 30 20 30 12b 18 10 18 10b 12 8b 8

167 100 60 100 60 100 40 50 30 40 20 30 18 25 18 20 12 18

250 80 80 50 80 50 80 30 50 25 40 20 30 18 25

333 100 80 100 60 100 40 60 40 50 25 40 20 30

500 60 80 50 80 40 60 30 50

750 80 80 60 100

1000 100

Note: Column A = 140-200% of transformer rating and Column B = 200-300% of transformer rating

Table 4 - Recommended Trans-Guard FX Mounted in a Dry Well Canister in Oil

(Maximum Oil Temperature of 100°° C)

Recommended Fuse Current Ratings (Amperes)

Fuse Voltage 8.3 kV 15.5 kV 23 kV

Transformer 3-Phase Voltage Rating (kV) Phase-to-Phase

2.4 4.16 4.8 7.2-7.96

8.32 12.47 13.2-

14.4 20.8 22.9-

24.9c 34.5c

3-Phase

Transformer

kVA A B A B A B A B A B A B A B A B A B A B

15 6 3 3 3a 3a 3a 3a 6a 6a 6a

22.5 8 10 6 6a 3 3 3a 3a 6a 6a 6a

30 10 18 6b 8 6 6a 3 3a 3a 6a 6a 6a

45 18 20 8 12 8b 10 6 6 3 3 6a 6a 6a

75 25 40 18 20 12 20 8 12 8b 10 6 6 6a 6a 6a

100 40 50 20 30 20 25 12b

18 12 18 8b 10 6 8 6a 6a 6a

112.5 50 60 25 40 20 30 12 20 12b

18 8b 10 8b 10 6 6a 6a

150 60 80 40 50 30 40 18 25 18 20 12 18 10b

12 6 6 6a

200 80 100

50 60 40 50 25 40 20 30 12 20 12b

20 8 10 8b 10 6

225 80 50 80 50 60 25 50 25 40 18 25 12 20 8 12 8 10 6b 8

300 80 100

60 80 40 50 30 50 20 30 20 30 12 18 12b

18 8b 10

500 100

80 60 80 50 80 40 50 40 50 20 30 18 25 12 20

750 80 80 50 80 50 80 30 50 25 40 20 30

1000 80 100

60 80 40 40 25 40

1500 100

50 40

2000 50

Note: Column A = 140-200% of transformer rating and Column B = 200-300% of transformer rating

Trans-Guard FX Full-Range Current-Limiting Fuses

January 2001 • Supersedes June 1997 • 2001 Hi-Tech Fuses, Inc. 6

Table 5 - Recommended Trans-Guard FX Mounted in Air at 40°° C Ambient Temperature

Recommended Fuse Current Ratings (Amperes)

Fuse Voltage

(5.5 kV) 8.3 kV 15.5 kV 23 kV

Transformer 3-Phase Voltage Rating (kV) Phase-to-Phase

2.4 4.16 4.8 7.2-7.96

8.32 12.47 13.2-

14.4 20.8 22.9-

24.9c 34.5c

3-Phase

Transformer

kVA A B A B A B A B A B A B A B A B A B A B

15 6 3 3 3a 3a 3a 3a 6a 6a 6a

22.5 8 6a 6a 3a 3a 3a 3a 6a 6a 6a

30 10b 12 6 6 6a 3 3a 3a 6a 6a 6a

45 12 18 8 8 6a 6a 3 3 6a 6a 6a

75 20 30 12 18 12b 18 8b 10 8 6 6a 6a 6a 6a

100 30 40 18 20 18 20 12 10b 12 8 6 6a 6a 6a

112.5 40 50 20 25 18 25 12b 18 12 8 8 6a 6a 6a

150 50 65 25 40 25 40 18b 20 12 18 10b

12 8b 10 6 6 6a

200 65 100 30 50 30 40 20 30 18 25 12b

18 12b 18 8b 8 8b 8 6a

225 65 100 40 65 40 50 25 30 20 30 12 18 12b 18 8 10

8b 8 6

300 100 (150)

50 80 50 65 30 40 25 40 18 25 18 20 12b

18

10

12 8b 8

500 (200)

250 80 (125)

80 125 50 65 40 65c 25 40 25 40 18 25

18

25 12b

18

750 250 (150)

(200)

125 (200)

65 100

65c 100c

40 65 40 65 25 40

20

40 18 25

1000 (200)

250 (200)

250 100

130

100c

125c

65 100

65 80 30 50

30

50 20 30

1500 250 160

200

130c

200c

100

130

80 130

50 50

30 50

2000 200

200c

250c

130

200

100

160

40

2500 160

200

130

200

50

3000 200

200

Note: Column A = 140-200% of transformer rating and Column B = 200-300% of transformer rating

Notes for Tables 3, 4 and 5:

§ Recommended fuses meet inrush criteria of 12 times transformer full load current for 0.1 second and 25 times

transformer full load current for 0.01 second. Fuses also meet cold load pickup criteria of 6 times transformer full

load current for 1 second and 3 times transformer full load current for 10 seconds.

§ Shaded areas indicate parallel fuse applications.

§ Ratings in parentheses are 5.5 kV rated fuses.

a Fuse allows greater than 300% of transformer rating.

b Fuse allows greater than 200% of transformer rating.

c Recommendations limited to gndY-gndY transformers with no more than 50% delta connected secondary load.

Phase-to-ground rated fuses are frequently recommended for gndY-gndY three phase transformers. For some

8.32 kV transformers, parallel 2” fuses (rated max. voltage 10kV) can be used for delta connected transformers.

Trans-Guard FX Full-Range Current-Limiting Fuses

January 2001 • Supersedes June 1997 • 2001 Hi-Tech Fuses, Inc. 7

Ordering Information:

To order the proper fuse for a particular application, first determine the correct fuse voltage and current

rating using either the appropriate application table (Tables 3-5) or the published performance data

(Tables 2a-2b, the applicable TCC and Peak Let-through Characteristics FC-016A). Then refer to Table 6

to determine the appropriate catalog number.

Table 6 - Trans-Guard FX Catalog Information

Catalog Number

Continuous

Current Rating

(amps) 5.5 kV 8.3 kV 15.5 kV 23.0 kV

3 - HTFX230003 HTFX240003 -

6 - HTFX230006 HTFX240006 HTFX250006

8 - HTFX230008 HTFX240008 HTFX250008

10 - HTFX230010 HTFX240010 HTFX250010

12 - HTFX230012 HTFX240012 HTFX250012

18 - HTFX230018 HTFX240018 HTFX250018

20 - HTFX230020 HTFX240020 HTFX250020

25 - HTFX230025 HTFX240025 HTFX250025

30 - HTFX230030 HTFX240030 HTFX250030

40 - HTFX230040 HTFX240040 HTFX250040

50 - HTFX230050 HTFX240050 HTFX250050

60 - HTFX230030 HTFX240030 -

65 - HTFX330065 HTFX340065 -

80 HTFX320080 HTFX330080 HTFX340080 -

80 - HTFX230040 HTFX240040 -

100 HTFX320100 HTFX330100 HTFX340100 -

100 - HTFX230050 HTFX240050 -

125 HTFX320125 HTFX330125 - -

130 - HTFX330065 HTFX340065 -

150 HTFX320150 - - -

160 - HTFX330080 HTFX340080 -

200 HTFX320200 - - -

200 - HTFX330100 HTFX340100 -

250 - HTFX330125 - -

Notes to Table 6:

1. To order a fuse having a blown fuse indicator, replace the 7th character (“0”) in the catalog number

with an “1” (EXAMPLE: HTFX241040). Please note that indicator fuses are not suitable for dry-well

canister applications. For an outdoor version (weatherproofed exterior surface), replace the 7th

character (“0”) in the catalog number with a “6” (EXAMPLE: HTFX246050).

2. Shaded current ratings shown are achieved by using a parallel combination of two fuses (order two

fuses).

No warranty or representation, expressed or implied, including any implied warranty of merchantability or fitness for a particular purpose regarding the product

described herein is extended by anything contained in this brochure. KHT Fuses, LLC neither assumes nor authorized any other person, firm or entity to assume for it

any liability in connection with the sale or use of the product described in this brochure. Any such warranties or other terms and conditions of sale of products shall be

in accordance with KHT Fuses, LLC standard terms and conditions of sale for such products, which are available on request.

KHT Fuses, LLC (a Hi-Tech Fuses Company)

415 19th St. Dr. SE, Hickory, NC 28602 Phone: 828-322-1855 Fax: 828-322-2376 Internet:www.hi-techfuses.com

Trans-Guard FX Full-Range Current-Limiting Fuses