Kyoritsu 5kV High Voltage Insulation Tester

A. Product Overview

The Kyoritsu KEW 3125A and KEW 3125B are professional high voltage insulation resistance testers used for testing the quality and condition of electrical insulation.

These instruments are designed for industrial electrical maintenance where conventional low voltage insulation testers may not be sufficient.

Key capabilities include:

• Selectable test voltages of 250 V, 500 V, 1000 V, 2500 V and 5000 V
• Insulation resistance measurement up to 1 TΩ
• PI or Polarization Index measurement
• DAR or Dielectric Absorption Ratio measurement
• Live circuit voltage warning
• Noise filter for stable readings in electrically noisy environments
• Bar graph and digital measurement display
• Suitable for high voltage electrical equipment
• CAT IV 300 V and CAT III 600 V safety classification

The KEW 3125A is the earlier version, while the KEW 3125B is its updated replacement model.

B. Working Principle

The Kyoritsu 5kV insulation tester works by applying a controlled DC test voltage across the insulation being tested.

The user selects the required test voltage depending on the equipment and insulation rating. The tester applies this voltage between the conductor and earth or between two conductors.

A very small leakage current passes through the insulation. The instrument measures this leakage current and calculates the insulation resistance.

The basic principle is:

Insulation Resistance = Applied Test Voltage divided by Leakage Current

Good insulation normally produces very high resistance, while damaged, contaminated, wet or deteriorated insulation produces comparatively lower resistance.

The KEW 3125A and KEW 3125B can also calculate diagnostic values such as PI and DAR by monitoring how the insulation resistance changes over time.

C. Why It Is Used

A 5kV insulation resistance tester is used to identify deterioration in electrical insulation before it leads to equipment failure, electrical leakage, short circuits or breakdown.

The Kyoritsu KEW 3125A and KEW 3125B can be used for:

• Testing insulation resistance of motors
• Testing transformers
• Testing high voltage and low voltage cables
• Testing generators and alternators
• Testing switchgear and electrical panels
• Testing industrial electrical installations
• Preventive electrical maintenance
• Commissioning new electrical equipment
• Detecting moisture inside insulation
• Identifying ageing or damaged insulation
• Comparing insulation condition during periodic maintenance
• Performing PI and DAR insulation diagnostic tests

Regular insulation testing helps maintenance teams identify developing electrical faults before they result in unexpected shutdowns.

D. Suitable Buyers

The Kyoritsu KEW 3125A and KEW 3125B are suitable for:

• Electrical maintenance engineers
• Industrial maintenance departments
• Electrical contractors
• Electrical testing companies
• Power generation companies
• Transformer manufacturers and service companies
• Motor manufacturers and rewinding workshops
• Cable manufacturers and cable testing companies
• Electrical panel manufacturers
• Substation maintenance teams
• Utility companies
• Factories and manufacturing plants
• EPC contractors
• Facility management companies
• Electrical safety inspection agencies
• Testing and calibration laboratories

The instrument is particularly suitable for professionals who regularly test motors, transformers, cables and other equipment requiring insulation test voltages up to 5000 V.

Frequently Asked Questions

1. What is the Kyoritsu KEW 3125B?

The Kyoritsu KEW 3125B is a high voltage insulation resistance tester capable of applying test voltages up to 5000 V and measuring insulation resistance up to 1 TΩ.

2. What is the difference between KEW 3125A and KEW 3125B?

The KEW 3125A is the earlier model, while the KEW 3125B is its newer replacement. Both are designed for high voltage insulation resistance testing up to 5kV.

3. What test voltages are available in the Kyoritsu KEW 3125B?

The tester provides selectable insulation test voltages of 250 V, 500 V, 1000 V, 2500 V and 5000 V.

4. What is the maximum insulation resistance measurement?

The Kyoritsu KEW 3125 series can measure insulation resistance up to approximately 1 TΩ, depending on the selected test range.

5. Can KEW 3125B test motors?

Yes. It can be used for insulation resistance testing of industrial motors and motor windings.

6. Can the Kyoritsu 3125B be used for transformer testing?

Yes. The KEW 3125B is suitable for checking transformer winding insulation and other high resistance insulation systems.

7. Can it be used for cable insulation testing?

Yes. The instrument is suitable for testing electrical cables, power cables and other insulated conductors where higher test voltages are required.

8. What is PI in an insulation tester?

PI or Polarization Index compares insulation resistance measurements taken at different time intervals during a test. It is commonly used to evaluate the overall condition of electrical insulation.

9. What is DAR in the KEW 3125B?

DAR or Dielectric Absorption Ratio compares insulation resistance values measured over a shorter period. It provides additional information about insulation quality and contamination.

10. Why is a 5kV insulation tester required?

A 5kV insulation tester is commonly required for testing higher voltage equipment, large motors, transformers, generators and power cables where lower test voltages may not adequately evaluate insulation condition.

11. Is KEW 3125A still available?

The KEW 3125A is the older model, and the KEW 3125B is its replacement model. Availability of the KEW 3125A can therefore depend on remaining stock.

12. Where is the Kyoritsu KEW 3125B used?

It is widely used in factories, substations, power plants, electrical maintenance departments, transformer service facilities, motor workshops and industrial electrical testing applications.