is an abbreviation for high potential.
Traditionally, Hipot is a term given
to a class of electrical safety testing
instruments used to verify electrical
insulation in finished appliances,
cables or other wired assemblies,
printed circuit boards, electric motors,
normal conditions, any electrical
device will produce a minimal amount
of leakage current due to the voltages
and internal capacitance present within
the product. Yet due to design flaws
or other factors, the insulation in
a product can break down, resulting
in excessive leakage current flow.
This failure condition can cause shock
or death to anyone that comes into
contact with the faulty product.
Hipot test (also called a Dielectric
Withstand test) verifies that the
insulation of a product or component
is sufficient to protect the operator
from electrical shock. In a typical
Hipot test, high voltage is applied
between a product's current-carrying
conductors and its metallic chassis.
The resulting current that flows through
the insulation, known as leakage current,
is monitored by the hipot tester.
The theory behind the test is that
if a deliberate over-application of
test voltage does not cause the insulation
to break down, the product will be
safe to use under normal operating
conditions¡Xhence the name, Dielectric
addition to over-stressing the insulation,
the test can also be performed to
detect material and workmanship defects,
most importantly small gap spacings
between current-carrying conductors
and earth ground. When a product is
operated under normal conditions,
environmental factors such as humidity,
dirt, vibration, shock and contaminants
can close these small gaps and allow
current to flow. This condition can
create a shock hazard if the defects
are not corrected at the factory.
No other test can uncover this type
of defect as well as the Dielectric
types of Hipot tests are commonly
used. These three tests differ in
the amount of voltage applied and
the amount (or nature) of acceptable
breakdown Test. The test voltage is
increased until the dielectric fails,
or breaks down, allowing too much
current to flow. The dielectric is
often destroyed by this test so this
test is used on a random sample basis.
This test allows designers to estimate
the breakdown voltage of a product's
Withstand Test. A standard test voltage
is applied (below the established
Breakdown Voltage) and the resulting
leakage current is monitored. The
leakage current must be below a preset
limit or the test is considered to
have failed. This test is non-destructive
and is usually required by safety
agencies to be performed as a 100%
production line test on all products
before they leave the factory.
Resistance Test. This test is used
to provide a quantifiable resistance
value for all of a product's insulation.
The test voltage is applied in the
same fashion as a standard Hipot test,
but is specified to be Direct Current
(DC). The voltage and measured current
value are used to calculate the resistance
of the insulation.
hipot tester is an electronic device
used to verify the electrical insulation
in a cable, printed circuit board,
electric motor, transformer or other
wired assembly. A Hipot tester is
used to perform a high potential test.
Generally a hipot tester consists
source of high voltage,
A current meter,
A switching matrix used to connect
the high voltage source and the current
meter to all of the contact points
in a cable.
In addition to these parts a hipot
tester may also have a microcontroller
and a display to automate the testing
process and display the testing results.
A hipot tester can be very similar
to a cable tester and often the two
are combined into a single device.
A hipot tester is used to verify that
circuits that should be insulated
are well isolated. It does this by
applying a high voltage between the
circuits and making sure no current
a typical wired assembly a hipot test
should connect all circuits in common
to ground. Then, one by one the tester
will disconnect a given circuit from
ground and connect that circuit to
high voltage. The current that flows
is monitored to verify that it is
being designed today usually must
comply with product safety regulations.
Some of these regulations work to
reduce the chance of you receiving
a harmful electrical shock. Modern
equipment is more likely to follow
these regulations. When it comes to
hipot charge, energy, and voltage
you should select the "safest"
machine that will still test your
minimize your risk of injury from
electrical shock make sure your hipot
equipment follows these guidelines:
total charge you can receive in a
shock should not exceed 45 uC.
The total hipot energy should not
exceed 350 mJ.
The total current should not exceed
5 mA peak (3.5 mA rms)
The fault current should not stay
on longer than 10 mS.
If the tester doesn't meet these requirements
then make sure it has a safety interlock
system that guarantees you can not
contact the cable while it is being
These guidelines come from the test
standard EN61010-1, Safety requirements
for electrical equipment for measurement,
control and laboratory use, April
1993, CENELEC. Over the last decade
many of the safety regulations have
been harmonized (standardized) and
EN61010-1 is similar to UL 61010A-1
you are testing cables there are several
things you can do to reduce the risk
the correct operation of the safety
circuits in the equipment every time
you calibrate it.
Follow all of the manufacturer's instructions
and safety guidelines.
Don't touch the cable during hipot
Allow the hipot testing to complete
before removing the cable.
Wear insulating gloves.
If you have any health condition that
can be aggravated by being startled
then don't use the equipment.
Don't allow children to use the equipment.
If you have any electronic implants
then don't use the equipment.
Test Where To Apply High Voltage?
understand a how hipot testing works
you'll need to understand where to
connect the high voltage supply. Hipot
testers usually connect one side of
the supply to safety ground (Earth
ground). The other side of the supply
is connected to the conductor being
hipoted. With the supply connected
like this there are two places a given
conductor can be connected: high voltage
you have more than two contacts to
be hipot tested you connect one contact
to high voltage and connect all other
contacts to ground. Testing a contact
in this fashion makes sure it is isolated
from all other contacts.
happens when you test something more
complicated than just contacts? A
series of contacts that are connected
with wires, resistors, capacitors,
diodes, and other components is called
a "network" of connections
(or "net"). To hipot test
a net you connect all of the contacts
in the net to high voltage and connect
all other contacts in the device to
ground. For example, if you have a
wire that connects two pins, the high
voltage will be simultaneously apply
to both of those pins and the entire
wire will be raised in voltage. All
other wires and pins will be held
at ground. If you have a resistor
that connects two pins, both pins
are raised in voltage, the voltage
drop across the resistor is always
zero. The entire resistor is raised
in voltage. In short, all pins of
a component see the same voltage at
all times. Applying the voltage in
this fashion makes sure the body of
the component is isolated from the
rest of the device.
Where is the current measured?
the hipot test the current that flows
out of the high voltage supply is
HiPot test procedure includes testing
the current at 2 mA amd 5 mA for connectors
and parts requiring this testing.
There are 2 sets of coils (Transmit
& Receive) wich are tested. We
test both coils together.
What causes current to flow
through an insulator?
"does not conduct." But
if you use enough voltage even the
best of insulations will allow some
current to flow. You may wonder why
the current flows? There are several
reasons current will flow through
insulation during a hipot test. Resistance,
capacitance, arcs, electrochemical
effects, and corona are all effects
that describe current flow. All of
these effects add together during
a hipot test to shape the outcome
of the test.
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