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RE: Short circuit/Control Panel - 220 V relay coils

Subject: RE: Short circuit/Control Panel - 220 V relay coils
  Date: Sun, 8 Jun 1997 05:06:38 -0700 (PDT)
  From: gweaver <gweaver-at-earthlink-dot-net>
    To: Tesla List <tesla-at-pupman-dot-com>


In my experience at work most motor starter coils are 120 VAC.  Most
control
panels have a 120 VAC control circuit transformer to supply the required
voltage.  Most factories have 480/240 VAC incomming to the building. 
Its
very rare to find a piece of industrial equipment the is designed to run
only on 240 VAC. Most of the wiring in an industrial building is 480
VAC.
Using one hot wire to ground will give 240 VAC on a 480 VAC line and 120
VAC
on a 240 VAC line.

At work I have tried doubling up fuses in an emergency to keep the
assembly
line running.  Using a renewable fuse I have found that putting equal
rated
fuses in parallel works fine.  I have put 6 10 amp fuses in parallel to
get
60 amps on a 480 VAC circuit.  3 20's will give 60 amps also.  2 20's
and 2
10's will not work for 60 amps because the 10's take most of the load
and
blow then the 20's are over loaded and they blow.

At home I have found that I can double up on circuit breakers as long as
they have the same amp rating.  2 15 amp breakers in parallel will give
30
amps but a 10 amp and 20 amp breaker in parallel does not give 30 amps. 

I have several motor starters an home that are all rated 120 VAC.  I
find
motor starters all the time at the scrap yard.  Most are nema size 0 and
nema size 1 but I have one motor started rated 200 amps.  I have been
thinging about using the 200 amps starter for my large TC but had not
given
it much thought for the smaller TC's.  


At 07:13 PM 6/7/97 -0500, you wrote:
>Subject:  RE: Short circuit/Control Panel - 220 V relay coils
>  Date:   Sat, 7 Jun 97 06:19:21 UT
>  From:   "William Noble" <William_B_Noble-at-msn-dot-com>
>    To:   "Tesla List" <tesla-at-pupman-dot-com>
>
>
>just a comment - a coil rated 220 VAC will work fine if you build a
>simple 
>bridge rectifier and give it 110 DC - add a capacitor (filter) of 20 to
>100 
>microfarads to keep the coil from buzzing and to give it a bit more
>voltage.
>
>snip  -----
>. Be aware that most of
>the contactors out there are using 220 volt relay coils. If that is
>all you can find (and you need a 110 type), then get a 110 to 220
>volt transformer to power the coil. The contacts can be used for
>either 110 or 220.
>snip
>
>