How to use insulation testers - Hioki

Components of an insulation tester

The figure illustrates the name of each part of the Hioki Insulation Tester IR.

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"Product List" of the insulation testers, please refer to here.

Insulation resistance measurement

Warning: Do not attempt to measure insulation resistance on a live conductor.

・    Verify that the MEASURE key is not in the raised position ([1] in the figure).
・    Consult the table and determine the measurement voltage to which to set the rotary switch ([2] in the figure).
・    Connect the black test lead to the ground side of the object being measured. [3]
・    Connect the red test lead to the line to be measured. [4]
・    Press the MEASURE key. [5]
・    Read the value after the inductor has stabilized. [6]

*This list provides an overview of how to use insulation testers. Please consult the user manual for your product to ensure safe and proper use.
*Please note that values in the table apply to testing in Japan.

Discharging function

To properly discharge, be sure to perform as shown below after the measurement.

・    Without removing the test leads from the item being measured, release the MEASURE key.
・    The built-in discharge circuit automatically discharges the item.
・    The discharge will end when the “discharge mark” on the right side of the display disappears.

*This list provides an overview of how to use insulation testers. Please consult the user manual for your product to ensure safe and proper use.
*Please note that values in the table apply to testing in Japan.

Voltage measurement

Notes: Test leads should only be connected to the secondary side of a breaker.
Never press the MEASURE key while measuring voltage.

・    Use the rotary selector to select the V function.
・    Connect the black test lead to the ground side of the object being measured.
・    Connect the red test lead to the line side of the breaker.
・    Read the value after the indicator has stabilized.

*This list provides an overview of how to use insulation testers based on the Hioki Model IR. Please consult the user manual for your product to ensure safe and proper use.
*Please note that values in the table apply to testing in Japan.

Resistance measurement

Before measurement, perform zero adjustment to cancel the test leads’ wiring resistance and other potentially problematic quantities.

・    Set the rotary selector to the Ω function.
・    Short circuit the tip of the test lead.
・    Pull up the MEASURE key.
・    Turn off the MEASURE key to hold the measured value.
・    Press the “０Ω　ADJ” key.
・    Connect the test lead to the ground side of the object being measured
・    Press MEASURE key and read the displayed value.
・    Turn off the MEASURE key after using.
The figure is an example of checking the continuity of ground wiring.

*This list provides an overview of how to use insulation testers based on the Hioki Model IR. Please consult the user manual for your product to ensure safe and proper use.
*Please note that values in the table apply to testing in Japan.

"Product List" of the insulation testers, please refer to here.

PVΩ measurement (Insulation Tester IR only)

PVΩ measurement is used to measure insulation resistance between a solar panel and ground. The PVΩ measurement allows accurate resistance measurements without the effect from power generation.

・    Turn OFF the main switch to the connection box to be discontinued from the power conditioner.
・    Turn OFF all disconnect switches used for strings.
・    Check that MEASURE key has been turned OFF. [1]
・    Set the rotary switch to “PVΩ".
・    Press the PVΩ 500V⇔V key and set the voltage to 500 V or V. [3]
・    Press the “500V/V RELEASE” key to release the lock. [4]
・    Connect the black test lead to the ground terminal. [5]
・    Connect the red test lead to terminal P of the string. [6]
・    Press the MEASURE key. [7]
・    A resistance will be indicated after approximately four seconds. [8]
・    Turn OFF the MEASURE key. [9]

• What is insulation resistance tester?
• Purpose of the insulation resistance tester?
• The principle of insulation resistance tester?
• Types of Insulation Resistance Testers
• Insulation resistance tester for EV

What is insulation resistance tester?

Insulation resistance tester, also known as megohmmeter or megger, is an electronic instrument used to measure electrical insulation resistance.

Purpose of the insulation resistance tester?

Insulation resistance testers are commonly used in the electrical industry to check the insulation integrity of wires, cables, transformers and other electrical equipment. By measuring insulation resistance, a technician can determine if the insulation is sound, if there are any defects, or if the insulation has degraded over time. This test is often used to identify potential safety hazards or to diagnose problems with electrical equipment such as motors, transformers and cables. In general, a higher insulation resistance indicates better insulation quality and a lower risk of electrical hazards.

Insulation resistance testing is important for several reasons, including:

Safety: Insulation Resistance testing helps ensure the safe use of electrical equipment by detecting any insulation faults that could result in electric shock or fire hazards.

Maintenance: Insulation resistance testing helps detect early signs of insulation degradation, allowing timely repair and replacement of affected equipment.

Compliance: To ensure compliance with safety and performance requirements, many industry standards and regulations mandate periodic insulation resistance testing of electrical equipment.

Troubleshooting: Insulation resistance testing can solve electrical problems by identifying the electrical fault or source of the fault.

Overall, insulation resistance tester is an essential tool in ensuring the safety, reliability and compliance of electrical equipment.

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The principle of insulation resistance tester?

First, the working principle of insulation resistance tester is based on the fact that insulating materials have a very high resistance to electrical current.

Insulation resistance testers utilize a high-voltage DC signal to be applied to the insulator being tested, and subsequently gauge the current that travels through the insulator. The tester then calculates insulation resistance by dividing the applied voltage by the measured current.

Testers typically have a range of voltage settings, depending on the type of insulation being tested. For example, a lower voltage setting can be used to test low-voltage cables, while a higher voltage setting can be used to test high-voltage cables or motors.

In addition to measuring insulation resistance, some insulation resistance testers can also measure other parameters, such as polarization index (PI) and dielectric absorption ratio (DAR), which can provide additional information about the condition of the insulation.

It is important to note that insulation resistance testing should only be performed by qualified personnel and proper safety precautions should be taken to avoid injury or equipment damage.

Types of Insulation Resistance Testers

With the advancement of technology, the insulation resistance testers on the market today include the following types:

Analog Insulation Resistance Testers: These are traditional insulation resistance testers that use an analog meter to display readings. They are simple to use, but not as accurate as digital testers.

Digital Insulation Resistance Testers: These testers use a digital display to show the readings and are more accurate than analog testers. They may also have other features, such as automatic ranging and data logging.

Megohmmeter: A megohmmeter is an insulation resistance tester specially designed to measure high insulation resistance values. They are commonly used for testing high-voltage equipment and systems.

Handheld Insulation Testers: These testers are portable and battery-operated, making them ideal for field testing. Both analog and digital formats are available.

Benchtop Insulation Testers: These testers are larger and more powerful than handheld testers and are designed for use in a laboratory or workshop environment.

Automatic Insulation Testers: These testers are computer controlled and can automate a variety of tests, making them ideal for testing large numbers of items quickly and efficiently.

Each of the above types has its disadvantages and advantages. When we choose, we can choose the right one according to the specific needs.

Insulation resistance tester for EV

Perhaps most of the insulation resistance testers on the market are aimed at fuel vehicles. But for electric vehicles, insulation resistance testing is equally important. If we are going to use an insulation resistance tester for EV, please note the following:

① Make sure the EV is not charging and the battery is disconnected.

② Connect the insulation resistance tester to the EV's electrical system according to the manufacturer's instructions.

③ Set the insulation resistance tester to a voltage level suitable for the EV system.

④ Turn on the insulation resistance tester and let it stabilize.

⑤ Measure the insulation resistance and compare it with the manufacturer's recommended value. If the resistance is too low, it may indicate a problem with the insulation.

⑥ Repeat the test on different parts of the electrical system, including the battery, charging system and motor.