I need to know how to select the free wheeling protection diode for the circuit? the load is wire wounded resistor of 115 ohm with 3.5 Kilo watt.

Can any one suggest me is protection diode required in this case? and if yes please let me know how to select.

  • \$\begingroup\$ Free wheeling diode mostly used for inductive load. \$\endgroup\$ – Sathyanarayanan G Jun 1 '16 at 8:07
  • \$\begingroup\$ Yes. But wire wound resistor also having considerable amount of parasitic inductance. We have to some protection while the load is switched off. How to find the inductance in this case and how to select the free wheeling diode is my query. \$\endgroup\$ – Ajit Kumar Jun 1 '16 at 8:31
  • \$\begingroup\$ See Why you using the resistor here i think to dissipate power. Inductive load if we not provide free wheeling diode means the energy stored in the inductive load dissipate and cause damage to winding. If want know the selection of the free wheeling diode check this electronics.stackexchange.com/questions/110574/…. \$\endgroup\$ – Sathyanarayanan G Jun 1 '16 at 8:40
  • \$\begingroup\$ Thanks for your quick response. Yes we are wanted to use the wire wound resistors to dissipate some 3.5 Kilo Watt with some switching device. In this case on what basis do I need to select the free wheeling diode? \$\endgroup\$ – Ajit Kumar Jun 1 '16 at 8:52
  • \$\begingroup\$ As a rule of thumb, use a freewheeling diode that can handle the same current as is being supplied to the load (inductors are like pseudo-constant current devices) \$\endgroup\$ – Sam Jun 1 '16 at 10:14

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