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DC Hipot Tester

What is DC Hipot Tester

DC hipot tester are used for everything from very low voltage devices to high voltage equipment. For medium to high voltage rotating equipment, DC hipot tests called step voltage or ramp tests are used to see whether the start of an insulation breakdown can be detected.

Benefits of DC Hipot Tester

Increased Efficiency.
One of the key benefits of using an DC hipot tester is the increased efficiency it offers. These testers are equipped with advanced features such as automatic test sequences and data logging, which allow for faster and more accurate testing. This can help companies save time and resources, leading to improved productivity and overall cost savings.

Enhanced Safety.
Safety is always a top priority when working with electrical equipment, and DC hipot tester are designed with this in mind. These testers come with built-in safety features such as ground fault detection and overvoltage protection, helping to prevent accidents and ensuring the well-being of operators. By using an DC hipot tester, companies can create a safer work environment and reduce the risk of electrical hazards.

Consistent and Reliable Results.
Another benefit of using an DC hipot tester is the consistent and reliable results it provides. These testers are calibrated to industry standards and offer precise measurement capabilities, ensuring that the test results are accurate and trustworthy. This is essential in quality control processes, where even minor variations in insulation resistance can have a significant impact on the performance of electrical equipment.

Versatility.
DC hipot tester are versatile tools that can be used in a wide range of industrial applications. Whether testing cables, transformers, motors, or circuit boards, these testers can handle a variety of testing scenarios with ease. This versatility makes them a valuable investment for companies operating in different sectors, providing a single solution for all their insulation testing needs.

Remote Monitoring and Control.
With the rise of Industry 4.0 and the Internet of Things (IoT), DC hipot tester now offer remote monitoring and control capabilities. Operators can access test results in real-time and make adjustments to test parameters from anywhere with an internet connection. This not only streamlines the testing process but also allows for better monitoring of equipment performance and predictive maintenance planning.

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Why Choose us

Customized solutions

We understand that each client's needs are unique, so we can tailor solutions to meet your specific requirements to meet individual client needs.

Quality control

We strictly abide by the international quality management system and strictly control every link from raw material procurement, production process, product quality inspection, etc. to ensure the stability and reliability of our products and services.

Our service

The company has a professional sales team to provide you with high-quality pre-sales consulting services. During the order production process, customers can communicate with us at any time to understand the production progress. At the same time, we provide high-quality after-sales service to meet the different needs of customers.

Difference Between AC Hipot Test And DC Hipot Tester

AC Hipot Tester
With an ac hipot tester, a long ramp time is usually not needed. The AC testing also has the benefits of checking both polarities of voltage and not requiring to discharge of the DUT after completing the testing. This testing also has its fair share of disadvantages – the test must consider the effects of both real and active currents. When an AC voltage is applied, the flowing current equals the voltage divided by the impedance.

But the impedance is complex as it contains both resistive and capacitive components.

The two components are out of phase with each other and combine in a complex manner to form the total current. As the magnitudes of these compounds can be different, the leakage current of a product with large amounts of capacitance can, with some testers, increase significantly without getting detected by the test.

DC Hipot Tester
A DC hipot tester applies a voltage with gradual steps, commonly known as ramping. It pauses after every increase to allow the capacitance of the DUT to absorb a charge and stabilise. The time needed for the charging current to decay after every step is known as the stabilisation time. The current flowing post the stabilisation time has passed represents the leakage current via insulation.

In case the voltage steps are too large, the sharp rise in charging current when the step gets applied might exceed the high current limit, causing the test to fail prematurely. It is important to carefully match the magnitude and timing of the steps to the characteristics of the DUT.

As a DC hipot tester charges the capacitance of a DUT, the charge itself proves to be a hazard to testing personnel. It must be removed after the test is over.

Direct Current High Voltage Test Machine

What Are The Tips For Using The DC Hipot Tester?

Like other instruments such as multimeter, DC hipot tester is an instrument for measuring resistance. The theoretical basis of DC resistance and three-phase resistance is Ohm's Law. The equipment adopts an advanced programmable constant current source, which can apply a constant high-precision current to external loads. The accuracy of the data obtained by the instrument and the accuracy of the actual resistance are improved. These are not available for non DC hipot tester. For resistance measuring instruments without constant current source, due to the increase of load, the current and other data obtained by the instrument itself will have a certain deviation, which will affect the test results.

Now let's talk about the quick test tips of using the transformer DC hipot tester:

The main casing must be reliably grounded during the test.

When measuring the inductive load, do not remove the test line directly to avoid endangering the tester and equipment due to inductive discharge. The output terminal of the machine is equipped with a discharge circuit. When the output is turned off, the inductor will discharge energy through the instrument. Do not remove the test wire until the discharge indication is completed.

During the test, irrelevant items are not allowed to be stacked on or around the equipment panel.

Please check the power supply voltage before starting: AC 220V ± 10% 50Hz.

When replacing the fuse and accessories, please use the same model. Pay attention to moisture and oil contamination.

During the test, please confirm that the tested equipment has been powered off and disconnected from other live equipment.

DC Hipot Tester Test Process

IC—Capacitive
Capacitive (or geometric capacitive) current is also called inrush current. The windings have capacitance. Current is required to elevate its voltage potential. Capacitive current typically drops to zero within seconds after the test voltage provided by the motor tester is stable.

IA—Absorption
Absorption current is present during atomic and any molecular polarization of the insulation, and is the current of interest during a PI test. This current will drop to zero, or near zero, over a period of time that varies by motor. The drop can happen in seconds or may take 10 minutes or more.

IG—Volume Conduction
Volume conduction current is the current that flows through the entire volume of the insulation between ground and the conductors. In good windings, this current is usually zero or near zero, and depends on the composition and condition of the insulation system. People sometimes think of this current as “leakage” current. The volume conduction current certainly leaks through the insulation, but the surface conduction current (IL) is usually the main leakage in a used motor.

IL—Surface Conduction

Surface conduction current is often referred to as surface leakage current. The surface conduction current runs over the end winding surfaces of the insulation.
Surface conduction is a result of surface contamination, dirt and moisture on the windings that are connected to ground.
As the contamination level increases, the resistance of the contamination drops, and the current increases.
As the voltage increases, the current increases more or less proportionally with the voltage applied by the motor tester.
For used, good motors, this current will dwarf the absorption and volume conduction currents because of the relatively lower resistance in the surface contamination.
For new, totally clean, and dry motors this current should be zero or near zero.

Breakdown Current1
The current discharged as a result of insulation failure. The peak value of this current may be very high, reflecting the energy stored in the capacitance of the winding. Normally, this current cannot be accurately measured.

Breakdown Voltage1

The voltage at which a disruptive discharge takes place through the volume or over the surface of the insulation.
High Direct Voltage (Also Referred to As Over-Voltage)1
A unidirectional voltage whose magnitude is greater than the peak value of the nominal RMS line-to-ground rating of the insulation system under test.

Measuring DC Voltage

DC voltage is applied to open (disconnected) windings by the DC hipot tester or motor analyzer. The DC voltage potential in the windings is rapidly raised to a predetermined level, or raised in steps up to this level, depending on what test method is used.
As the voltage is raised, several currents will flow into and possibly out of the windings to ground. The combined total of these currents are measured by the hipot tester. Currents present are the same as those in an insulation resistance test.

Insulation Failure

Electrical insulation failure or breakdown is usually indicated by an arc, a sharp capacitive discharge, at the failure location. There are times when failure or partial failure is indicated by a large abnormal change in the measured current or by erratic behavior of the measured current.
Warnings of insulation breakdown by accelerating measured current can start within as little as 5% of the breakdown voltage, however, it can also start much earlier.

Precautions For Operation Of DC Hipot Tester

The operator must wear an insulating rubber cover and place an insulating rubber pad under his feet to prevent life-threatening high-voltage electric shocks;

The DC hipot tester must be reliably grounded;

When connecting the object under test, it is necessary to ensure that the high-voltage output "0" is in a timely "reset" state;

During the test, the ground terminal of the DC hipot tester must be reliably connected to the object under test, and no open circuit is strictly prohibited;

Do not short-circuit the output ground wire and the AC power line, so as to avoid high voltage on the shell and cause danger;

Avoid short-circuiting between the high-voltage output terminal and the ground as much as possible to prevent accidents;

Once the test lamp and ultra-leakage lamp are damaged, they must be replaced immediately to prevent misjudgment;

Before troubleshooting, the power supply must be cut off;

When the DC hipot tester adjusts the high voltage with no load, the leakage current indicates an initial current, which is normal and does not affect the test accuracy;

Avoid direct sunlight on the DC hipot tester, and do not use or store it in a high temperature, humid and dusty environment;

After the DC hipot tester has been used for one year, it must be sent to the measurement department or returned to the factory for verification in accordance with the requirements of the national technical supervision department. It can only be used after passing the test.

The Composition Of The Front Panel Of The DC Hipot Tester

1) Power switch.

2) Reset button: When pressed, the test light is off, and there is no high voltage output at this time;

3) AC-DC conversion switch: When it pops up, it is AC test; when it is pressed, it is DC test;

4) Start button: When pressed, the test light is on, and the instrument outputs high voltage at this time;

5) Voltage regulator: Adjust the output voltage, the counterclockwise is small, and the clockwise is large;

6) Leakage current preset adjustment button: Press the preset switch to continuously set the leakage current alarm value 0.3~2mA/2~20mA;

7) Leakage current preset/test switch: Press the preset switch, it is the preset state, window B shows the leakage current alarm value; pop up the preset switch, it is the test state, window B shows the actual detected leakage current value;

8) Leakage current range selection switch: Switch the leakage current indication ammeter range;

9) Remote control socket: Plug in the remote control plug, and the instrument can be controlled through the switch on the high voltage rod.
output for remote control.

10) High voltage output: DC high voltage output;

11) Test light: When the light is on, it means that the high voltage has been activated, and when the light is off, the high voltage is disconnected;

12) High voltage output: AC high voltage output;

13) Grounding post: Used to connect the test grounding wire;

14) High-voltage output meter head: It can monitor the high-voltage output situation intuitively;

15) Time timer: 1~99 seconds timing adjustment, you can set the required test time value;

16) Timing switch: Press the timing test switch and adjust it arbitrarily within 99 seconds; when it pops up, the timer does not work and is manual;

17) Time display window: When the timer is turned on, the high-voltage output will be automatically cut off after the output reaches the set time;

18) Super-leakage light: When the light is on, it means that the object under test breaks down and the super-leakage is unqualified;

19) Leakage current display window: According to the position of "leakage current range switch", the corresponding indication is 0~2mA/2~20mA;

20) Voltage display window: Output voltage value display;

Our Factory

Beijing Huazheng Technology Co., Ltd. was established in 2023, headquartered in Beijing, China. It is an enterprise with outstanding innovation capabilities in the field of high voltage testing equipment. Our mission is to provide customers with high-quality and efficient solutions, with the goal of promoting social progress and sustainable development. Our values are integrity, innovation, and collaboration, always putting customers first. Our strengths lie in our technical strength, quality control, customer service, and partnership. We have a professional R&D team and advanced production equipment, which can provide innovative solutions and high-quality products. We strictly adhere to the international quality management system, ensuring the stability and reliability of our products and services. We have established a comprehensive pre-sales, sales, and after-sales service system to provide customers with comprehensive support and solutions. The long-term cooperative relationship established with well-known domestic and foreign enterprises has further promoted the development of the industry. We will continue to uphold the concepts of integrity, innovation, and excellence, and contribute more to the development of the high voltage test equipment . Choose Beijing Huazheng Technology Co., Ltd., choose trust and success.

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Asked Questions

Q: How long does a DC hipot test take?

A: The voltage applied to the winding must be gradual, to avoid exceeding the maximum test voltage. Its duration is typically one minute (most cases), and can be as long as ten minutes (some cases), counted from when the maximum voltage value is reached.

Q: What is the acceptable leakage current for a hipot test?

A: Because the insulation resistance and reactance of the stray capacitance is so high, the ac test current can be simplified to the leakage current at 250 V times the ratio of hi-pot test voltage to 250 V. If the test voltage is 3000, then the test current would be 3000/250 x 0.5 or 6 mA.

Q: Is DC hipot testing destructive?

A: The conclusion from this experiment is that the relatively low energy available in the DC hipot test will not cause damage to the insulation system as long as the test is performed in accordance with the standards.

Q: What causes hipot test failure?

A: A hipot failure is caused by a breakdown in the insulation. It is indicated by an abrupt increase in the current flowing as a result of the application of the test voltage. A real breakdown is usually obvious: the arc can be seen. Sometimes it cannot be seen but it can be heard.

Q: What is the acceptable value of hipot test?

A: A general rule of thumb for establishing the hipot test voltage is two times the working voltage + 1000 V. For a working voltage of 220 V, the rule of thumb test voltage is (2 × 220 + 1000) = 1440 V. Therefore, 1500 V is a common hipot test voltage. Hipot test voltage may be specified as either ac or dc.

Q: Why we need so high voltage in the hipot test?

A: A Hipot test is necessary to test the stress of an electronic device for safety and quality purposes. Under high voltage it checks that there is no breakdown or perforation occurring, and that insulation distances on the line and in the air are respected.

Q: What are the precautions for hipot test?

A: Safety Recommendations for Setting Up a Hipot Testing Workstation
Decide Where the Testing Station Will Reside. ...
Ensure Adequate Power. ...
Avoid or Take Extra Precautions With Metal Objects. ...
Create Enough Space Within the Workstation. ...
Position the Testing Equipment Appropriately. ...
Include Safety Features.

Q: How does DC hipot tester work?

A: How DC Hipot Tests Work. A DC over-voltage potential is applied to the windings, and the current to ground is measured with a resolution of 1 pA for the iTIG and 10nA for the Power Pack. This current includes leakage from the windings as well as other currents such as surface currents on the outside of the windings.

Q: How much leakage current is acceptable in a hipot test?

A: As a result of the voltage difference between the conductors, current flow would be observed. No breakdown of either the air insulation or the solid insulation should take place. Furthermore, current should not be more than 5mA peak (3.5mA rms)

Q: What is the leakage current in DC hipot test?

A: Using the formula I = 377VC, find the leakage current I (in amps) by multiplying the voltage that your hipot test is conducted at (V) by the capacitance you measured between line and ground (C), and multiplying that product by 377. This will give you the anticipated leakage current I (in amps).

Q: What is the difference between AC and DC hipot tester?

A: The main difference between the two tests is that High Voltage AC Hipot test applies an alternating voltage to the cable at a frequency between 50 to 60 Hz. On the other hand, a High Voltage DC Hipot test applies a direct voltage to the cable.

Q: What is the voltage for DC hipot tester?

A: The best voltage for a DC hipot is normally higher than the AC test voltage by a factor of 1.414. A product that would be tested at 1500V AC would be tested at 2121V DC. For double-insulated products, the required test voltages may be much higher, such as 2500 VAC or even 4000 VAC for a 120 VAC power tool.

Q: Can DC hipot tester check DC voltage?

A: The DC hipot tester measures voltage or current and it is suitable for both AC and DC voltage.

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