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B or not to B

Discussion in 'Datasheets, Manuals and Component Identification' started by Lurch180, May 14, 2018.

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  1. Lurch180

    Lurch180

    15
    0
    Aug 16, 2017
    Hi, can someone please explain what the difference is with an IRFP460C and a IRFP460BPBF

    I have a treadmill and the circuit has a short on the IRFP460C and the only one I can buy from RS Components is the IRFP460BPBF

    Will this do the same job, I've looked at data sheets and can't see any difference.

    Thank you for looking / advise

    Paul
     
  2. WHONOES

    WHONOES

    746
    161
    May 20, 2017
    The IRFP460BPBF is lead free. Other than that it is the same although the "B" version does appear to be fully insulated.
     
  3. Lurch180

    Lurch180

    15
    0
    Aug 16, 2017
    Thanks Whonoes, much appreciated
     
  4. 73's de Edd

    73's de Edd

    2,761
    1,155
    Aug 21, 2015
    Sir Lurch180 . . . . .

    Vel l l l l . . .I am dun bin tellink you vat . . . . It seems like there is the initial device number and as any upgrades are made, they assign A . . . . . B . . . . C suffixes onto the device alfa / number string.
    Soooooooo I believe, that in your units not so critical, application, ( Not VERY HIGH FREQUENCY switching at HIGH current levels) any of the string would work for you.

    I do see that Digi key is offering the C version but it is being in the old case profile versus the newer insulated unit in its polycarbonate clad shell . . . . .tomatos . . .tomatoes ?

    https://media.digikey.com/pdf/Data Sheets/Fairchild PDFs/IRFP460C.pdf

    The other case of marking cryptics is the very ending . . . . . of PB . .for . .lead . . . .F for free = PBF lead free leads.
    BUT . . . . . don't we old timers LIKE our lead . . . . . just like the fresh smell of Napalm in the morning.

    Addenda I now see that WHONOES has come on twixt my poking and later posting.

    73's de Edd
    .....
     
  5. Lurch180

    Lurch180

    15
    0
    Aug 16, 2017
    Thanks 73's de Edd, I think I understand your thread, I have now ordered the BPBF version and will fit it when it arrives, fingers crossed it repairs the treadmill, I'm getting bigger, must run soon. lol
     
  6. Lurch180

    Lurch180

    15
    0
    Aug 16, 2017
    Hi Guys, I bought the and fitted the component and now the motor starts to smoke after its been running for about 2 minutes.
    I checked the resistance across the coil and the reading is 18.5 ohms.
    The label on the motor reads 1.75HP, 230VDC, 4800 rpm
    Using ohm's law. I divided the V by ohms and got 12.57 A
    I then multiplied the A by V and got 2891 W
    I googled HP and found that 746W is equal to 1HP, therefore 1.75HP multiplied by 746W = 1305.5W
    Using this new data, I found that the resistance across the coil should be 40.52 ohms.
    My question is please can you confirm that I have worked this out correctly and the coil windings are too low.
    Therefore making my motor faulty.
    thank you
     
  7. Harald Kapp

    Harald Kapp Moderator Moderator

    9,499
    1,957
    Nov 17, 2011
    You cannot use the resistance of a motor winding to evaluate power. A motor develops a counter EMF when running. The counter EMF reduces the effective voltage across the motor and ths reduces the effective power consumption.
    There is possibly an issue with the correct sequence of control signals for the MOSFETs.
     
  8. Lurch180

    Lurch180

    15
    0
    Aug 16, 2017
    Thanks Harald, are you able to give me any idea why after the motor has been running it wants to smoke at the brushes end. The motor doesn't get warm and the brushes look OK.
    The motor speed is controlled by the DCV and that is working OK.
    The windings measured this morning are reading 20 Ω.
    What should it be?
    Thanks
    Paul
     
  9. 73's de Edd

    73's de Edd

    2,761
    1,155
    Aug 21, 2015
    AC-DC motors normally arc a bit at the commutator bar / brush contact unions, if you have some spray contact cleaner, direct a stream at those areas and see if the condition abates for that instant of the stream presence..
    Also take note of the commutator bar oxidation conditions .. . are they blackened, or a shiny copper ?
     
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