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What's wrong with this schematic....

  • Thread starter Paul Hovnanian P.E.
  • Start date
S

Spehro Pefhany

Jan 1, 1970
0
Well it is for relay coil protection. I don't think I've ever seen a
better-protected relay coil.

d

Pearce Consulting
http://www.pearce.uk.com


Yes, if the open DO doesn't protect it, the dead short across the coil
surely will. ;-)

However, it implies it's only an issue when "multiple inductive
devices in parallel" are wired to one DO, so if you just have one big
honking solenoid, you're fine.



Best regards,
Spehro Pefhany
 
J

John Fields

Jan 1, 1970
0
R

Rich Grise

Jan 1, 1970
0
---
Perhaps a reply to this email, which I sent to [email protected]


<QUOTE>
After having viewed this page:

http://www.veris.com/info/apps/app01.htm

It appears that your current measuring equipment is connected in
parallel with the mains. If that's so, how does it measure current?

Maybe the "Veris Current Sensor Relay Coil" is that multiple inductive
load they're talking about - it's in parallel with the "AC Relay Coil",
as far as I can see.

Thanks,
Rich
 
S

Spehro Pefhany

Jan 1, 1970
0
---
Perhaps a reply to this email, which I sent to [email protected]


<QUOTE>
After having viewed this page:

http://www.veris.com/info/apps/app01.htm

It appears that your current measuring equipment is connected in
parallel with the mains. If that's so, how does it measure current?

--
John Fields
Professional Circuit Designer
<END QUOTE>


will explain it all. ;)


Actually, I think that part of it's okay. The current sensor pickup
is a CT, but it also requires 24VAC/DC @10mA to operate. Drawing that
auxilliary supply from the contactor coil voltage is one way to do it.

http://www.veris.com/pdf/cs/proving/hp/pv-digital/h735_i0d.pdf



Best regards,
Spehro Pefhany
 
J

John Woodgate

Jan 1, 1970
0
I read in sci.electronics.design that John Fields

Why did you not mention the complete short-circuit at the right-hand end
of the schematic?
 
F

Fred Bloggs

Jan 1, 1970
0
..or can just anyone put stuff on the internet?

http://www.veris.com/info/apps/app01.htm

There's nothing "wrong" with the circuit because it isn't a circuit. It
is a notional illustration of types of loads producing "kickback"
paralleled by types of components that suppress "kickback"- the
multitude of devices should have been a clue.
 
R

Rich Grise

Jan 1, 1970
0
I read in sci.electronics.design that John Fields


Why did you not mention the complete short-circuit at the right-hand end
of the schematic?

Nobody saw it until you pointed it out. :)
 
J

John Fields

Jan 1, 1970
0
I read in sci.electronics.design that John Fields


Why did you not mention the complete short-circuit at the right-hand end
of the schematic?
 
J

John Woodgate

Jan 1, 1970
0
I read in sci.electronics.design that amdxjunk
When the 24vac switch is closed no current is supplied to the circuit. See
upper left corner of circuit.
That's to protect the 24 V supply from the short-circuit at the other
end.
 
F

Fred Bartoli

Jan 1, 1970
0
John Woodgate said:
I read in sci.electronics.design that amdxjunk

That's to protect the 24 V supply from the short-circuit at the other
end.

Which is here to protect the TVS that prevents the MOV from wearing off,
once the resistor in the RC has opened.

Clever...
 
C

Carl D. Smith

Jan 1, 1970
0
Why did you not mention the complete short-circuit at the right-hand end
of the schematic?

Wow. I didn't see it either. I was looking too hard for other
problems like the power switch that can't connect power to the
circuit. :)
 
F

Franc Zabkar

Jan 1, 1970
0
I read in sci.electronics.design that amdxjunk

That's to protect the 24 V supply from the short-circuit at the other
end.

The missing link was fusible.


- Franc Zabkar
 
P

Paul Hovnanian P.E.

Jan 1, 1970
0
Fred said:
There's nothing "wrong" with the circuit because it isn't a circuit. It
is a notional illustration of types of loads producing "kickback"
paralleled by types of components that suppress "kickback"- the
multitude of devices should have been a clue.

The dead short is a particularly effective suppresser.
 
F

Fred Bartoli

Jan 1, 1970
0
Paul Hovnanian P.E. said:
The dead short is a particularly effective suppresser.

Well, it depends on the number of turns.
 
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