Original poster: "davep by way of Terry Fritz <teslalist-at-qwest-dot-net>" <davep-at-quik-dot-com>
I may be off base, however some MOTOR STARTERS look like
CONTACTORS. Some MOTOR STARTERS have built in overcurrent
protection...
??
Tesla list wrote:
>Original poster: "Richard W. by way of Terry Fritz <teslalist-at-qwest-dot-net>"
><potluck-at-xmission-dot-com>
>The contactor will be the master switch for the system. The deadman switch
>is in series with the coil. There is also an over-current circuit that will
>shutdown the system in case of extreme currents. Before this system is put
>into actual use I want to make sure the contacts can survive opening with a
>minimum amount of burn. I've found variac brushes to be expensive and
>contacts for a contactor are expensive to replace as well. Aside from that
>a welded contact would mean a very unsafe condition allowing power
>to flow in a situation where shutdown should have occured.
>Rick W.
> > The contact opens as in shuts off?
>>Maybe your the coil is dropping out because it's not
>>getting whatever it needs to hold the contacts closed. Is it an AC or DC
>>coil?
Fair question. 'DC' coils will operate on AC, tho
takes some thought to get tem reliable. Likewise
AC coils on DC.
> > Subject: Contactor question
> > > Scenario:
> > > Variac stack feeding a 10Kva pig 240vac at 35 amps.
> > > 2 poles on the contactor are being used (red and black wires)
> > >
> > > Contactor
> > > Arrow Hart Size 3
> > > 240v 25hp 1 phase
> > > 120 FLA
> > > 720 LRA
> > >
> > > Under the above conditions the contactor opens....
> > > Do I need some kind of arc protection and if so how?
> > >
> > > Thanks
--
best
dwp
.