Subject: 38kV Trans-Guard™ OS Shorty Backup Curre nt-Limiting Fuses Date: 2/8/09
File: PCUP-09-001_OS Page: 1
The 38kV Trans-Guard™ OS Shorty is a backup type current-limiting fuse specifically
designed for use in 26.4-34.5kV distribution and wind farm transformers that have a primary or
secondary delta connection or that feed more than 50% delta connected load. Its ability to significantly
reduce fault energy and its very high interrupting capability provide state-of-the art protection against
today’s ever-increasing available fault currents.
As a back-up type current-limiting fuse (refer to ANSI C37.40 for fuse definitions), the 38kV Trans-
Guard™ OS Shorty must always be applied in series with a properly-sized low current protective
device. The device typically used with this fuse is a 34.5kV under-oil weak link expulsion fuse. The
expulsion fuse and the current-limiting fuse are each selected to provide fault protection over a certain
range of currents. The expulsion fuse is chosen to clear the low magnitude currents such as those
caused by faults that occur external to the transformer and high impedance faults within the
transformer. Such currents are generally below the minimum interrupting current rating of the current-
limiting fuse. The back-up type current-limiting fuse is selected so as to clear all other currents. In
addition to interrupting the fault currents resulting from low impedance faults within the transformer, the
back-up current-limiting fuse serves the very important function of limiting the amount of energy that is
let through to the source of the fault to a value below the withstand capability of the transformer tank.
By doing this, the current-limiting fuse minimizes the likelihood of disruptive equipment failures (i.e.
transformer tank ruptures, accessories being damaged or broken loose from their mountings, etc.). No
other protective device is available to similarly reduce the risk of disruptive transformer failures.
Subject: Trans-Guard EXT CLF – Eyebolt Terminals Improvement Date: 2/8/09
File: PCUP-08-003_EXT Page: 2
Features Benefits
• L-L voltage rating
Allows smaller backup fuses to be used in order to
substantially reduce arcing time and energy let-through
during a fault. This provides increased transformer
protection and greatly improves upstream coordination.
• Broad range of ratings
Makes it possible to provide current-limiting protection
for transformers as large as 2850KVA at 26.4kV,
3000KVA at 27.6kV, and 3800KVA at 34.5kV.
• Rigorous testing to meet ANSI/IEEE
standards
Internal quality requirements including 100% physical
inspection, resistance measurement, and helium mass
spectrometer leak testing
• Durable design
For long life including machined brass end caps,
filament wound high temperature epoxy tubular bodies,
sand filler and hermetic sealing system
• High fault current interrupting capability
25,000 amperes symmetrical
ELECTRICAL CHARACTERISTICS:
Notes:
1. All fuses have a rated maximum interrupting current of 25,000 A rms symmetrical.
2. Peak arc voltages quoted are for 25,000 A currents at the rated maximum voltage listed.
Reduced voltages and currents will reduce the peak arc voltage. Consult the factory for
information.
65 HTSS372065 450 2,600 11,600
80 HTSS372080 570 5,600 23,500
100 HTSS372100 720 9,500 36,100
125 HTSS372125 950 19,300 68,000
165 HTSS372165 102 1,200 43,500 155,000
38.0 38.0 104
Minimum
I/C
(Amps)
Minimum
Melt I2T
(A2Sec)
Maximum
Total I2T
(A2Sec)
Nominal Fuse
Voltage
Rating (kV)
Current
Rating
(Amps)
Fu se
Catalog
Number
Rated
Maxim um
Voltage
(kV)
Peak Arc
Vo l tage
(kV)
(2)
Subject: Trans-Guard EXT CLF – Eyebolt Termin als Improvement Date: 2/8/09
File: PCUP-08-003_EXT Page: 3
DIMENSIONAL INF ORMATION:
Nominal
Fuse
Voltage
Rating
(kV)
Current
Rating
(Amps)
Fuse
Catalog
Number
Overall
Diameter
(A)
Overall
Length
(B)
Body
Length
(C)
Fuse
Weight
65 HTSS372065
80 HTSS372080
100 HTSS372100
125 HTSS372125
19.29-19.41”
(490.0-493.0mm) 18.29-18.37”
(464.6-466.6mm) 12.0lb
5.44kg
38.0
165 HTSS372165
3.25-3.32”
(82.5-84.3mm)
21.94-22.06”
(557.3-560.3mm) 20.94-21.02”
(531.9-533.9mm) 13.5lb
6.12kg
B
C
A
¼-20 threaded hole
½” deep
Subject: Trans-Guard EXT CLF – Eyebolt Termin als Improvement Date: 2/8/09
File: PCUP-08-003_EXT Page: 4
FUSE SELECTION
For a detailed explanation on selecting the appropriate backup current limiting fuse for a given
application, please refer to Hi-Tech Fuses Application Bulletin FS-10. For a quicker method of
selecting the proper 38kV Trans-Guard™ OS Shorty fuse for applications involving coordination with
ABB 34.5kV under-oil weak link expulsion fuses please refer to the following table.
ABB 34.5kV Protective Links (345B995G__) & 38kV Trans-Guard OS Shorty Fuses
Note:
Backup fuses are selected to melt only on internal transformer faults, where
transformer impedance is equal to, or greater than, the value given. For transformers
having lower impedances, consult the factory.
Z% Link Shorty Link Shorty Link Shorty
75 1.6 2 65 2 65 2 65
112.5 1.8 3 65 3 65 2 65
150 2.0 3A 65 3A 65 3 65
225 3.0 4 65 4 65 3A 65
300 3.5 5A 65 5 65 4 65
500 4.0 6 65 6 65 5A 65
750 5.75 7 65 7 65 7 65
1000 5.75 8 80 8 80 7 65
1100 5.75 8 100 8 80 7A 80
1250 5.75 9 125 9 125 7A 80
1500 5.75 9 125 9 125 8 100
1750 5.75 9 125 9 125 9 125
1850 5.75 10 165 9 125 9 125
2000 5.75 10 165 10 165 9 125
2250 5.75 10 165 10 165 9 125
2500-2850 5.75 10 165 10 165 10 165
3000 5.75 10 165 10 165
3250-3800 5.75 10 165
A ssumed
Impedance TRAN S FORM ER VO LTAGE (kV) L-L
KVA 26.4 34.527.6
