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Induced Over Voltage or DFDV Test Set


Neo Tele-Tronix Pvt. Ltd. better known by brand name NTPL serves in the field of Electrical and Testing Equipments over 35 years located in Kolkata, West Bengal. NTPL manufactures over 60 different types of test and measuring instruments.

Induced Over Voltage Test Set ( IOVT)  known as Double Voltage Double Frequency Test Set (DVDF). Apart from DVDF it can be customized to higher voltages and higher frequency according to the need of the customer.

It is used for conducting tests of different capacity of transformer.

It is used for testing the inter turn and inter layer insulation within the winding of the transformer. According to the IS, the relevant testing method is that an alternating voltage of sine wave form at double frequency and double amplitude is applied at the L.T. terminals of the transformer under test.

The higher frequency is applied to avoid excessive excitation current during the test.

In this process the voltage is allowed to increase upto a specified value and allowed to remain there for the particular time required (i.e. not more than 1 minute).

A transformer with poor inter turn and inter layer insulation will fail to withstand the test.

MANUFACTURING RANGE :  NTPL manufactures DVDF/Induced Over Voltage Test Set of different capacity suitable to test transformers of capacity ranging from several kVA to several MVA.


  • Input Voltage : 400V/415V, 3 phase 4 wire,50Hz.
  • Output Voltage : upto 1200V
  • Output Frequency : any one of the 100Hz, 150Hz, 200Hz output as selected during enquiry/order. Or may be available in different selectable frequency mode/continuously variable frequency mode (i.e. 90Hz to 200Hz) with variable speed.
  • One 3 phase Induction Motor is driven by means of Squirrel Cage Motor with a 3 phase continuously variable Autotransformer to generate Voltage.
  • Interlock and Protection : Zero Start Interlock, Door interlock, Single Phasing Preventor, Over Load and Short Circuit.
  • Metering : Digital
  • Measurement Scheme : CT & PT operated scalable integrated current & voltage measurement. Digital Frequency meter to indicate input & output frequency.

        Designed & Manufactured according to relevant IS and International Standards.

NOTE : Specification & design can be altered according to special requirement of the customer.