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Franklin tester designed by TASK's in house experts is used to check the following parameters:-

  1. Surface resistance
  2. Resistance distribution
  3. Coating thickness (optional)
  4. Determination of surface resistance of individual samples of electrical steel and punched parts
  5. Quality control of insulation coating
  6. Manually operated or fully automatic version
  7. Preparation and execution of the measuring process according to ASTM-standard A 717-81and IEC 60404-11


Operating principle

The following video gives a brief insight into the operation of TASK's Franklin Tester



It is used to measure the total current which flows along the insulation coating of the sample when pressure is applied via several contacts, and to convert the measured value to an equivalent surface resistance. It is suitable especially for quality control of insulation coating.

Constructed from 2 main components:

1.Voltage supply unit
2.Testing device with hydraulic pump
The test head consists of two longitudinal rows of five vertically mounted steel rods which are free to move axially against the surrounding spiral springs. A stainless steel measuring contact is positioned at each end of each rod. It is possible to move the test head hydraulically perpendicular to a surface.

The testing contacts are pressed onto the insulation coating with a pressure of 129N per electrode. An electrical contact to the steel sheet is created with a spiral drill. If the resistance is finite a current proportional to the resistance flows through the insulation coating.

Technical data:

Testing voltage:0.5 V, 1 mV resolution

Accuracy of settings:0.5 %

System accuracy:1 %

System resolution:1 mV

Measuring unit for hydraulic pressure:0 bis 25 bar ± 5 % (1290 N ± 5 %)

Test head:10 Electrical contacts

Measuring Surface Area: 6.45 cm² ± 1 %

Maximum testing pressure:25 bar (displayed value)

Supply voltage:230 V AC, 50 Hz