Do I need the suppressor next to the fuel pump?
Discussion
Hi,
Was just wondering what the suppressor next to the fuel pump is for, Is it for the radio? Its just that when I was underneath it doing some work the lead was broken anyway.
ifAlso when the pump is running, I I put the brake lights on or turn the headlamps on etc the note changes, it still runs but I cant hear it, bad earth maybe?
cheers.
Was just wondering what the suppressor next to the fuel pump is for, Is it for the radio? Its just that when I was underneath it doing some work the lead was broken anyway.
ifAlso when the pump is running, I I put the brake lights on or turn the headlamps on etc the note changes, it still runs but I cant hear it, bad earth maybe?
cheers.
carl350i said:
Hi,
Was just wondering what the suppressor next to the fuel pump is for, Is it for the radio? Its just that when I was underneath it doing some work the lead was broken anyway.
ifAlso when the pump is running, I I put the brake lights on or turn the headlamps on etc the note changes, it still runs but I cant hear it, bad earth maybe?
cheers.
Mine hasn't been on since I rebuilt the car a couple of years ago.... No difference.Was just wondering what the suppressor next to the fuel pump is for, Is it for the radio? Its just that when I was underneath it doing some work the lead was broken anyway.
ifAlso when the pump is running, I I put the brake lights on or turn the headlamps on etc the note changes, it still runs but I cant hear it, bad earth maybe?
cheers.
A suppressor is not fitted just to reduce radio interference. As you will remember from school a motor works by placing an electromagnet in a fixed magnet. As the motor goes round and round you have to find some way of transferring power to the rotating bit. As it is a motor you will also want to select different electromagnets to keep the rotation going. When you discontinue an electrical circuit particularly an inductive one it will still have energy and try to continue the current flow resulting in a spark. A suppressor placed across the contacts provides an alternative path for the energy to follow rather than jumping the gap and sparking.
Sparking on electrical switch contacts tends to erode the contact surface fairly quickly, more to the point however any sparking is probably best avoided when pumping fuel.
Sparking on electrical switch contacts tends to erode the contact surface fairly quickly, more to the point however any sparking is probably best avoided when pumping fuel.
steve-V8s said:
A suppressor is not fitted just to reduce radio interference. As you will remember from school a motor works by placing an electromagnet in a fixed magnet. As the motor goes round and round you have to find some way of transferring power to the rotating bit. As it is a motor you will also want to select different electromagnets to keep the rotation going. When you discontinue an electrical circuit particularly an inductive one it will still have energy and try to continue the current flow resulting in a spark. A suppressor placed across the contacts provides an alternative path for the energy to follow rather than jumping the gap and sparking.
Sparking on electrical switch contacts tends to erode the contact surface fairly quickly, more to the point however any sparking is probably best avoided when pumping fuel.
yes and in addition when the supply is switched of to the inductive circuit the Voltage level can be quite high as the field collapses the induced voltage is proportioinal to rate change flux, so you have to suppress this that why most relays have a "back flow diode across supply to absorb the energy of the coil when the supply is switched offSparking on electrical switch contacts tends to erode the contact surface fairly quickly, more to the point however any sparking is probably best avoided when pumping fuel.
instead as steve says burning out contacts on switch etc
Pardon my ignorance, but what's this 'rate change flux'?
I've tried googling:
I've tried googling:
wikipedia said:
In the field of electromagnetism and mathematics, flux is usually the integral of a vector quantity, flux density, over a finite surface. It is an integral operator that acts on a vector field similarly to the gradient, divergence and curl operators found in vector analysis. The result of this integration is a scalar quantity called flux.
but none the wiser. What's it mean in ingerlish?When current passes through a conductor it produces a magnetic field. If you wind the conductor into a coil you get a stronger magnetic field. Flux is a measure of how strong the magnetic field is. With a motor or relay coil the idea is to have a high flux density concentrated where you want the magnetic force applied. The energy that causes sparking comes from the magnetic field collapsing when the power is removed. It is the same principle that makes the high voltage for your spark plugs.
A magnetic field will generate a voltage in a conductor but only when the flux is changing. Hold a magnet near to a conductor and nothing will happen however move the magnet over the conductor and it will generate a voltage as the flux rises and falls (as per your alternator). The voltage generated is proportional to the rate of change. When you suddenly remove the voltage from a coil the magnetic field tends to collapse very quickly and the sudden change in flux density can generate a fairly high voltage.
Easiest way to understand flux density is with a fixed magnet and some iron filings. Put the magnet under a piece of paper and scatter the filings on top. It will reveal the lines of flux and more filings will be attracted to the higher density areas.
A magnetic field will generate a voltage in a conductor but only when the flux is changing. Hold a magnet near to a conductor and nothing will happen however move the magnet over the conductor and it will generate a voltage as the flux rises and falls (as per your alternator). The voltage generated is proportional to the rate of change. When you suddenly remove the voltage from a coil the magnetic field tends to collapse very quickly and the sudden change in flux density can generate a fairly high voltage.
Easiest way to understand flux density is with a fixed magnet and some iron filings. Put the magnet under a piece of paper and scatter the filings on top. It will reveal the lines of flux and more filings will be attracted to the higher density areas.
1 is a lot better than none and would do the job, to be honest the tolerance on these sort of capacitors is so huge that a 2 could well only be 1.5 or so anyway. If you really want to fit a 2 simply put a pair of 1 micro Farad parts in parallel, I would be happy with fitting a 1 in this application.
Gassing Station | Griffith | Top of Page | What's New | My Stuff