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Surge protection

Hi all,
I am working on a Engine - compressor based crawler machine.
having 24v DC system.
One microcontroller is used on the m/c for measurement of revolutions
of gear motor.
Problem:- Due to some 10-12 solenoid valves are also operated from the
same 24V DC source facing a problem of surges causing failure of
controller.
we tried to use diodes & capacitor combination across each solenoid to
suppress surges still the problem persist.

Please advise what modification can be done.
 
A

Abstract Dissonance

Jan 1, 1970
0
Hi all,
I am working on a Engine - compressor based crawler machine.
having 24v DC system.
One microcontroller is used on the m/c for measurement of revolutions
of gear motor.
Problem:- Due to some 10-12 solenoid valves are also operated from the
same 24V DC source facing a problem of surges causing failure of
controller.
we tried to use diodes & capacitor combination across each solenoid to
suppress surges still the problem persist.

Please advise what modification can be done.

Maybe a Varisitor? Is the power supply to the microcontrollers regulated?


A quick search in google returned

http://focus.ti.com/lit/an/slup100/slup100.pdf
 
D

Dan Hollands

Jan 1, 1970
0
Hi all,
I am working on a Engine - compressor based crawler machine.
having 24v DC system.
One microcontroller is used on the m/c for measurement of revolutions
of gear motor.
Problem:- Due to some 10-12 solenoid valves are also operated from the
same 24V DC source facing a problem of surges causing failure of
controller.
we tried to use diodes & capacitor combination across each solenoid to
suppress surges still the problem persist.

Please advise what modification can be done.

To suppress a coil operated from dc, a reverse diode across the coil with no
capacitor is usually all that is required.

When faced with this type of problem the whole system needs to be reviewed
for ways that the noise is getting to the ucontroller.
including wire routing, location of parts, filtering of power supply,
filtering on the ucontroller board, filtering of incoming and outgoing
signals, grounding etc. - this often takes experience and detective work to
solve. (Solving these problems is one way to gain experience)

Dan


--
Dan Hollands
1120 S Creek Dr
Webster NY 14580
585-872-2606
[email protected]
www.QuickScoreRace.com
 
P

Pooh Bear

Jan 1, 1970
0
Hi all,
I am working on a Engine - compressor based crawler machine.
having 24v DC system.
One microcontroller is used on the m/c for measurement of revolutions
of gear motor.
Problem:- Due to some 10-12 solenoid valves are also operated from the
same 24V DC source facing a problem of surges causing failure of
controller.
we tried to use diodes & capacitor combination across each solenoid to
suppress surges still the problem persist.

Please advise what modification can be done.

I barely know where to start. You've clearly got yourselves into a mess
through a failure to understand basic good design practice.

You probably have EMI problems - maybe also 'dirty grounds'. Without a
detailed knowledge of the product it's hard to say.

As the Irish would say " If I wanted to get there, I wouldn't start from
here " !

Graham
 
P

Pooh Bear

Jan 1, 1970
0
Dan said:
To suppress a coil operated from dc, a reverse diode across the coil with no
capacitor is usually all that is required.

When faced with this type of problem the whole system needs to be reviewed
for ways that the noise is getting to the ucontroller.
including wire routing, location of parts, filtering of power supply,
filtering on the ucontroller board, filtering of incoming and outgoing
signals, grounding etc. - this often takes experience and detective work to
solve. (Solving these problems is one way to gain experience)

Yes.

In short you need an expert. Something that was likely missing from the original
design team.

Graham
 
E

ehsjr

Jan 1, 1970
0
Hi all,
I am working on a Engine - compressor based crawler machine.
having 24v DC system.
One microcontroller is used on the m/c for measurement of revolutions
of gear motor.
Problem:- Due to some 10-12 solenoid valves are also operated from the
same 24V DC source facing a problem of surges causing failure of
controller.
we tried to use diodes & capacitor combination across each solenoid to
suppress surges still the problem persist.

Please advise what modification can be done.

It might be sags, not surges, if those solenoids draw a lot
of current. You could feed the 24V through a diode to a
big cap on the input of the voltage regulator that powers
the controller. When the solenoids operate, they can't suck
the charge off the cap due to the diode, so the controller
Vcc won't see the sag, if it exists.

Ed
 
P

Pooh Bear

Jan 1, 1970
0
ehsjr said:
It might be sags, not surges, if those solenoids draw a lot
of current. You could feed the 24V through a diode to a
big cap on the input of the voltage regulator that powers
the controller. When the solenoids operate, they can't suck
the charge off the cap due to the diode, so the controller
Vcc won't see the sag, if it exists.

It could be *almost anything* given the vagueness of the OP's post.

One would hope that they have at least used clamp diodes across the solenoid
coils.

I think we can safely assume that his uC isn't powered directly from the 24V
though. Since it'll be powered by some voltage regulator somewhere a good
question would be to enquire if the regulation is/isn't local and.or whether
it shares any current paths with the load(s) - look for 'ground noise'.

I'd also look very closely at trace loop areas to see if there's some
electromagnetic coupling between the solenoids' magnetic fields and the uC
inputs.

Graham
 
R

Rich Grise

Jan 1, 1970
0
Hi all,
I am working on a Engine - compressor based crawler machine.
having 24v DC system.
One microcontroller is used on the m/c for measurement of revolutions
of gear motor.
Problem:- Due to some 10-12 solenoid valves are also operated from the
same 24V DC source facing a problem of surges causing failure of
controller.
we tried to use diodes & capacitor combination across each solenoid to
suppress surges still the problem persist.

Please advise what modification can be done.

Separate the power leads at the battery, so that the solenoids and
the uP regulator have separate power/ground loops; optoisolate the
processor; ideally, use a separate battery for the uP.

Good Luck!
Rich
 
S

Sam Nickaby

Jan 1, 1970
0
Pooh Bear said:
I barely know where to start. You've clearly got yourselves into a mess
through a failure to understand basic good design practice.

You probably have EMI problems - maybe also 'dirty grounds'.

You mean like this product? http://www.apexi-usa.com/product_electronics_detail.asp?id=224&pageNum=1

This product looks expensive. But by using an extra isolated
battery just for the controller would be much more cost effective.
The question is how to separate the two power source once
the 10-12 solenoid valves begin to operate? I have about the
same dilemma as the OP for my car alarm that goes off during
driving when it's on the same battery as the car.
 
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