chris1373 Posted January 22, 2008 Report Share Posted January 22, 2008 Hi, i want to make a test bank to "test" generators. If i want to get 500kva from a 380 Volt gen, am i correct if i say: I = 500.000/(1.73*380), then I=760Amps, each phase. So, to use a star bank, R=220/760? R=0,29 ohms? Can any one help me? Thanks. Chris. Link to comment Share on other sites More sharing options...
chris1373 Posted January 24, 2008 Author Report Share Posted January 24, 2008 Guys, can any one help me? Please! I have a lot of iron and cantal res, but i want to know if they will work for the purpose. Please, help me my friends!!!!! Chris! Link to comment Share on other sites More sharing options...
marke Posted January 26, 2008 Report Share Posted January 26, 2008 Hello Chris Yes, that looks pretty good to me for a star connected load. Best regards, Mark Empson | administratorSkype Contact = markempson | phone +64 274 363 067LMPForum | Power Factor | L M Photonics Ltd | Empson family | Advanced Motor Control Ltd | Pressure Transducers | Smart Relay | GSM Control | Mark Empson Website | AuCom | Soft Starters Link to comment Share on other sites More sharing options...
chris1373 Posted January 28, 2008 Author Report Share Posted January 28, 2008 Marke, can you tell me or were to look the amps per mm^2 that stainless steel can handle? The resistors that i have seems to be made of stainless steel! Thanks in advance! Chris. Link to comment Share on other sites More sharing options...
chris1373 Posted February 6, 2008 Author Report Share Posted February 6, 2008 I know that Marke do his best, so, can any one else help me please? Chris! Marke, can you tell me or were to look the amps per mm^2 that stainless steel can handle? The resistors that i have seems to be made of stainless steel! Thanks in advance! Chris. Link to comment Share on other sites More sharing options...
marke Posted February 6, 2008 Report Share Posted February 6, 2008 Hello Chris Unfortunately, it is not as just a figure of Amps per square mm. You are looking for an intermittant rating. There is power dissipated in the resistors due to the current through them and their resistance. This power will cause a temperature rise that is dependent on the power dissipated and the thermal resistance of the resistors. The thermal resistance is a function of the total surface area of the resistors and the air flow through them. For short term overloads, you really need to know the transient thermal resistance for different time periods so that you can use the appropriate thermal resistance for the duration of the overload only. You also need to know the maximum operating temperature that is acceptable in your installation. Note, different grades of stainless steel will have different resistances. Best regards, Mark Empson | administratorSkype Contact = markempson | phone +64 274 363 067LMPForum | Power Factor | L M Photonics Ltd | Empson family | Advanced Motor Control Ltd | Pressure Transducers | Smart Relay | GSM Control | Mark Empson Website | AuCom | Soft Starters Link to comment Share on other sites More sharing options...
chris1373 Posted February 7, 2008 Author Report Share Posted February 7, 2008 Marke, i only need to know the minimum amps that my resistors can handle, not anything else! I can send you pictures of the the resistor if it helps! Please, give me a hand! Chris. PS: Is there any table you know for the current rating that stainless steel can handle, an aprox will do it? Hello Chris Unfortunately, it is not as just a figure of Amps per square mm. You are looking for an intermittant rating. There is power dissipated in the resistors due to the current through them and their resistance. This power will cause a temperature rise that is dependent on the power dissipated and the thermal resistance of the resistors. The thermal resistance is a function of the total surface area of the resistors and the air flow through them. For short term overloads, you really need to know the transient thermal resistance for different time periods so that you can use the appropriate thermal resistance for the duration of the overload only. You also need to know the maximum operating temperature that is acceptable in your installation. Note, different grades of stainless steel will have different resistances. Best regards, Link to comment Share on other sites More sharing options...
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