Transformer test system 2-in-1 MICROTEST 626X+7631 (Low Voltage + Safety)

Price: Contact

Model 626X+7631
Manufacturer MICROTEST
Power supply 98Vac-132Vac or 195Vac-264Vac
Weight 9 Kg / 15 Kg
Size 344 x 145 x 343 mm / 435 x 145 x 500 mm
Condition Stocking
Warranty 12 months

Transformer test system 2-in-1 MICROTEST 626X+7631 (Low Voltage + Safety) is a comprehensive solution that combines low-voltage electrical characteristics testing and safety compliance testing.

I. Specification of Transformer testing system 2-in-1 MICROTEST 626X+7631

Transformer test system 2-in-1 MICROTEST 626X+7631 (Low Voltage + Safety) offers 20 testing channels and integrates low-voltage testing (including inductance, leakage inductance, resistance, capacitance, etc.) with AC/DC withstand voltage insulation testing (up to 5000V/6000V)

MICROTEST 626X+7631 ensures efficient and convenient testing for transformer products.

To measure the inductance value of a transformer, you can use an LCR meter, which offers selectable test frequencies including 200kHz, 500kHz, and 1MHz. It supports software that allows connection to a PC, enabling the storage of test data.

  • Low Voltage Electrical Test
  • Hi pot/ Insulation Test
  • 20 Channels
  • Test Frequency (200k/500k/1MHz)
  • AC Voltage Output 5000V
  • DC Votage Output 6000V
  • Insulation Resistance 12000MΩ
  • One-stop test solution (Low Voltage + High Voltage Test Function).

II. Main features of Transformer test system 2-in-1 MICROTEST 626X+7631

MICROTEST 626X+7631 2-in-1 (Low Voltage Electrical Test + Hi pot/ Insulation Test):

  • All-In-One Low Voltage Electrical Test: Inductance (L)/Leakage Inductance/Turn Ratio/Resistance (DCR)/Resistance (R)/Balance/Capacitance (C)/Short Circuit.


Automatic Balancing Bridge & 4-Wire DCR Test (DC Resistance):

  • Check if the winding tension is improper for Transformer.


Turns ratio is an important parameter in transformer:

  • Ideally, we can get the turns ratio by compare the input and output voltage. However, there are many parameters that might affect. So, there are some different ways to detect turns ratio.


TR Voltage

Put a AC voltage on primary coil, and detect the voltage on secondary coil. Compare the turns ratio and phase.

TRL Inductance

Detect the inductance on each coil, and calculate the turns ratio. The turns ratio is more accurate on transformer with bigger leakage inductance.


Detect capacitance to make sure the insulation between winding position and winding coil is enough:

  • The winding coil on the transformer include distributed capacitance, it usually distribute between winding coil.
  • Capacitance is usually represented by the capacitance by one winding to another winding in an equivalent circuit.
  • Cs and Cp is an equivalent capacitance in series or parallel in equivalent circuit.
  • D value is the ratio with AC resistance and capacitance, The lower the D value, is better.


Test leakage by LCR balance bridge:

  • When the instrument connect a primary coil with the transformer and the secondary coil is under open status, the test result L= Lp on primary coil + Leakage Current.

→ The leakage inside the instrument must short the secondary coil in the transformer.

A ideal secondary coil’s voltage will be 0V in short status. The voltage on both side of primary coil will be 0V. The inductance from primary coil will be the real leakage current.


Safety certification testing items:

  • AC Hipot
  • DC Hipot
  • Insulation Resistance
  • Current Leakage.


AC/DC withstanding voltage test:


  • Difference between AC and DC.

AC Hi pot Test

Most DUT have parasitic capacitance. With AC test, might not able to charge the parasitic capacitance. Therefore, this will create constantly current go through.

DC Hi pot Test

The parasitic capacitance will be charged under DC hi-pot test. Therefore, the current will reduce to almost 0. 


  • Advantages for AC Test.

AC Hi pot Test

AC test is same as our normal usage electricity. Also, AC is able to do positive and negative polarity test. 
AC test won’t charge the parasitic capacitance on the DUT, so it won’t create instantaneous peak current. Do not need to discharge the DUT after testing.

DC Hi pot Test

The parasitic capacitance on DUT has been charged under DC test, so the rest leakage current is the real current from DUT.


  • Disadvantage of AC/DC Hi-pot Test.

AC Hi pot Test

NIf the DUT has huge parasitic capacitance, the current we detect will bigger then the actual current.
To fulfill the necessary current for the capacitance of the DUT, the output current is much more than DC test. This is danger for the operator

DC Hi pot Test

Testing Voltage has to increase from 0.
To fulfill the necessary current for the capacitance of the DUT, the output current is much more than DC test. This is danger for the operator.
The discharge process is necessary after DC hi-pot test. 
DC test can only do the single polarity test.


Hi-pot test time:

The testing voltage is refer to the condition of DUT while doing Hi-pot test. If the voltage setting is too low, the insulation material defect might not be detected. If the voltage setting is too high and the testing time is too long, it may cause the permanent damage for the material.


Normally setting for the safety standard.

  • Formula  →Testing Voltage= DUT recommend voltage × 2+1000V
  • EX : DUT standard :240V    →Setting test voltage:1480V.


Common way to safe time for testing.

  • Testing time for most products is 60s. If there are more than one test on one item, it will cost a lot of time. This will lower the efficiency og the product line.
  • Therefore, the product line usually shorter the testing time to 1~2 sec. and higher 10%~20% testing voltage.


What is insulation resistance test:

  • VDE and TUV safety standard request insulation resistance test for some specific product before hi-pot test. The reason is to make sure the insulation will not be damaged while doing hi-pot testing. Insulation resistance test is the key item to evaluate the material.
  • Hi-pot test is judge by leakage current, but IR test is judge by resistance, and usually it’s higher than 1 MΩ. It tests the DUT’s resistance between both terminal.

Why do we need to do IR test:

Confirm the performance of the structure of the insulation.

  • The insulation structure should have higher insulation resistance rate by using better material.
  • For the insulation material, the protection against electric shock of the switch must be guaranteed. Confirm the insulation structure can pass the reliability test(heat durability, insulation)
  • The importance of insulation resistance. Before assemble the product, IQC has to do the IR test for every components, such as switches, transformers, resistors, capacitors, inductors, PCB, wire or cable to make sure the quality.

Leakage current test:

→Measuring Tiny AC Leakage Current

  • DUT has tiny parasitic capacitance. This characteristic will create leakage current by resistance. Capacitor is a resistance component under AC voltage. This may cause the test result include the leakage current inside the instrument. If the DUT has low leakage current, we must consider capacitance , frequency, and the voltage we put.

Arc detection:

  • The surface or interior of the insulation material might discharge under high voltage test. Because of the lost of insulation performance, DUT may have temporary of discontinuity discharge.
  • Because that temporary discharge can’t be judge by leakage current, so Hi-pot tester will judge the defect product by the changing rate of testing voltage or leakage current.
  • Arc test is a geometric not a constant test. Also, the detection will be affect by the wire’s impedance or capacitance between the detectors. The rate of change of the current will be affect in the Arc detection.


Technical specifications of Transformer test system 2-in-1 MICROTEST 626X+7631 (Low Voltage + Safety)



Test Channel


Low Voltage Electrical Test









Frequency Resolution

5 digits

Basic Accuracy


AC Drive Level


DC Drive Level


Output Impedance



Inductance or Voltage
Test Freqeuncy:50Hz-200kHz

Test Mode

Meter Mode / List Mode

Parameters Measurement

Inductance (L)、Impedance (Z)、Capacitance (C)、Resistance (R)、Conductance (G)、Susceptance (B)、Admittance (Y)、Alternating Current Resistance (ACR)、Quality Factor (Q)、θ、Direct Current Resistance (DCR)、Leakage Inductance、Turn Ratio、Balance、Short Circuit


0.1nH ~ 9999.99H


0.00001pF ~ 999.99mF


0.00001 ~ 99999


0.00001Ω ~ 99.9999MΩ


0.01nS ~ 99.9999S


-180°~ +180°


0.1mΩ ~ 99.999 MΩ


0.1 ~ 99999.9 turns


12 pairs, between pin to pin

Hi pot/ Insulation Test


AC Hi pot

DC Hi pot


Output Voltage




Voltage Resolution




Voltage Accuracy

 Test Range




AC Arcing Detection



Measuring time


Ramp Time


Time Resolution





Transformer Tester

Hi pot Tester



  Built-in stroage

128 sets

15 sets

  PC Link-stroage

Unlimited storage

  Power Supply

98Vac-132Vac or 195Vac-264Vac

98Vac-132Vac or 195Vac-264Vac



  Power consumption


  Dimension (W*H*D)

344x145x343 mm (W*H*D)

 435x145x500 mm (W*H*D)


9 Kg



RS-232、Handler、LAN、USB Host、EXT. I/O

 RS-232、Remote、USB Host、USB Device、EXT.I/O


Color Screen, 7″ TFT

Color Screen, 4.3″ TFT



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