The following are the type tests recommended by the relevant IEC standard: A) Dielectric Test. B) Temperature Rise Test. C) Breaking Test. D) Tests For Time/Current Characteristics.

1. High Voltage Fuses Test
Techniques
Prepared by
Mohammad Mominur Rahman
Student ID:437106801

2. CONTENT
 Introduction
 High Voltage Fuses
 High Voltage fuse test technique
 Dielectric Test
 Temperature Rise Test
 Breaking Test
 Tests For Time/Current Characteristics

3. Introduction:
What is a fuse? The fuse is an electronic device, which is used to protect circuits
from over current, overload and make sure the protection of the circuit. There
are many types of fuses available in the market, but function of all these fuses is
same.

4. High Voltage Fuses:
In high voltage and high power applications, some additional design considerations come into play.
 CARTRIDGE TYPE HV HRC FUSE :- Its construction is similar to low voltage type except that some special
design features are incorporated.
 LIQUID TYPE HV HRC FUSE :- This fuses are filled with carbon tetra chloride & have the widest range of
applications in high voltage circuits.
They are employed for voltage transformer protection or for circuits up to about 400 A rating current on
systems up to 132KV or higher and may have breaking capacity of 6,100 A at 33KV (350 MVA , 3-phase).

5. High voltage fuse standard are covered by the 60282 series
60282-1 Current limiting fuses
60282-2 Expulsion fuses.
In addition, there are the following standards relating to specific applications:
60549 External protection of shunt capacitance.
60644 Motor circuit application.
60787 Transformer circuit application.

6. High Voltage fuse test technique:
The following are the type tests recommended by the relevant IEC standard:
A) Dielectric Test.
B) Temperature Rise Test.
C) Breaking Test.
D) Tests For Time/Current Characteristics.

7. Dielectric Test:
 Hipot Test is short name of high potential (high
voltage) Test and it is also known as Dielectric
Withstand Test. A Hipot test checks for “good
isolation.”
 Hipot test makes surety of no current will flow from
one point to another point.
 Hipot test is the opposite of a continuity test.
 Continuity Test checks surety of current flows easily
from one point to another point while Hipot Test
checks surety of current would not flow from one
point to another point (and turn up the voltage really
high just to make sure no current will flow).

8. Temperature Rise Test:
 Fuses have a specific electric resistance value. When exposed to current, their
temperature will rise depending on the load.
 Test results for temperature rises can vary significantly based on the type of fuse
connection used, and fuse performance is therefore measured using a standard
fuse (i.e., specified by a relevant industry standard).
Figure: Test results for temperature rises

9.  Because measurements of temperature rises in the lab will be different from
data obtained during actual driving, the general approach is to conduct a
second evaluation based on reliability tests for each vehicle model.
 Fuses with connection terminals made out of heat-resistant copper alloy are
able to withstand a temperature of up to 140°C.
 If we assume a temperature of 80°C inside the engine compartment, this
means the fuses can support a temperature increase of 60°C.

10. Breaking Test:
 Fuses are usually the ultimate backup protection in the circuits in which they
are included they must be capable of operating under the most onerous
conditions which may arise.
 For this reason the test at maximum breaking capacity are done under
specified conditions in low power factor (typically less 0.2). The tests
determine not only breaking capacity but also parameters.
 Because of the varied usage of high voltage fuses there are no maximum
breaking capacities specified in the IEC standards.

11. Tests For Time/Current Characteristics:
 Time-current characteristics are the most important
specifications of fuses.
 Fuses are designed to only withstand continuous current
that is equivalent to their rated current. When the current
flowing through a fuse exceeds the rated current, the fuse
must cut off the current within a predetermined time
interval, thus ensuring the current flow is interrupted.
 For this reason, the melting time of a fuse when exposed to
overcurrent is specified by international and national
standards for each type of fuse.
 In the case of BFMN fuses, which are the most common
type in use today, the applicable standards are ISO 8820-3
(international), JASO D612 (Japan) and SAE J2077 (US).
These standards specify uniform time-current
characteristics, which are regarded as the international
standard.
Figure: BFMN

12.  Time-current standard values specify an upper threshold for the melting time to prevent an overcurrent from
flowing continuously and resulting in fire or damage to connected electrical wiring and electric devices. This
is the ultimate purpose of a fuse.
 At the same time, a lower threshold is specified to ensure the current is not interrupted during the initial rush
at the start of the current flow, and thus ensure durability.
 Time-current characteristics differ by fuse type. For example, motor circuits employ slow blow fuses (SBF)
that feature a slow-blow mechanism to withstand the comparatively long current rush that is produced when
a motor starts operating.
Table : Rated values
Figure: Time-current characteristics