RE: Economizer circuit

[Tech Man <TechMan@hcitech.com>]

Yes, that's exactly what I meant.  Thanks for the correction. 

> -----Original Message-----
> From:	Bryan in San Jose Ca [SMTP:everuplate@eisa.com]
> Sent:	Friday, March 31, 2000 4:57 AM
> To:	ev@listproc.sjsu.edu
> Subject:	Re: Economizer circuit
> 
>  ......I think you meant to say, the cap is in parallel with the
> resistor.....When it is in series with the resistor, the cap fills up and
> the current falls to 0. That would allow a single switch, parallel R/C
> solution. Funny, but I reminded myself just now that I did it for a riding
> mower relay for my EV motorcycle. Amazing when you get older, it takes
> longer to remember things...
> 
> ----- Original Message -----
> From: Tech Man <TechMan@hcitech.com>
> To: <ev@listproc.sjsu.edu>
> Sent: Friday, March 31, 2000 6:25 AM
> Subject: RE: Economizer circuit
> 
> 
> > A much simpler and less costly approach is to use a capacitor in series
> with
> > the resistor and works as follows:  Before the capacitor is charged up,
> > it appears as a dead short and allows full current to reach the coil of
> the
> > contactor providing fast turn-on times. As soon as the
> > capacitor charges, it appears "open" so current can only flow through
> the
> > resistor dropping the current through the coil.  When power
> > to the coil is turned off, the capacitor discharges through the
> "bleeder"
> > resistor and is ready for the next cycle.  It is best to
> > determine the value of the capacitor experimentally since coil
> resistances
> > vary, but generally a good place to start is around 1500 mFd.
> > Also, make sure that the working voltage of the capacitor is appropriate
> for
> > the coil voltages involved.
> >
> > > -----Original Message-----
> > > From: Bryan in San Jose Ca [SMTP:everuplate@eisa.com]
> > > Sent: Thursday, March 30, 2000 6:39 PM
> > > To: ev@listproc.sjsu.edu
> > > Subject: Re: Economizer circuit
> > >
> > > Hi,
> > > Not a snubber, it's a circuit to reduce the power consumption in the
> coil
> > > while the relay is "on". A simple approach is a 2 stage circuit in
> which
> > > the
> > > first switch would "start" the relay by providing full coil voltage to
> > > engage the relay, then a 2nd switch would be turned on in parallel
> with
> a
> > > series resistor to "hold" the relay closed and lower the power
> dissipated
> > > in
> > > the coil when the first circuit is switched off. The overall power
> > > dissipated in the coil would instead be dissipated in the series
> resistor
> > > "hold" circuit.
> > > For this to work, you would have to find the minimum holding current,
> add
> > > some margin, then calculate a series resistor value for the hold
> circuit.
> > > Need more help? drop a line....
> > >
> > > For their built in version, they use a PWM circuit instead of the
> simple
> > > external resistor approach.
> > >
> > > Hope this helps...
> > >
> > >
> > > ----- Original Message -----
> > > From: Michael Bearden <techsan@pacbell.net>
> > > To: <ev@listproc.sjsu.edu>
> > > Sent: Thursday, March 30, 2000 7:48 PM
> > > Subject: Economizer circuit
> > >
> > >
> > > > OK, I bought a contactor(Kilovac)which says (on the case) 'Requires
> > > > economizer circuit"...Is this the "snubber" which I have seen
> discussed,
> > > > or a different animal altogether?
> > > > Michael B.
> > > >
> >