Stamps and AC Noise Reset, Non-Issue

Archiver

Thanks Chris,

Thanks for the reply and the testimonial.

I too, have had zero problems with "noise generating a reset" type of
problem.

If this is happening to someone they probably have a power supply
problem.

Ron

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Original Message

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From: "Chris Anderson" <fes@g...>
To: <basicstamps@egroups.com>
Sent: Monday, June 12, 2000 1:45 PM
Subject: Re: [noparse][[/noparse]basicstamps] Basic Stamp PLC Style Application Board


> I have a bs2sx mounted 25mm (1 inch) away from a 40Amp solid state
relay
> switching a 240 volt ac motor with zero problems ever, outside noise
> should'nt be a problem with the reset. Also am very interested in
the PLC
> replacement option.
>
>
>

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Original Message

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> From: Valles, Alfredo <AValles2@v...>
> To: <basicstamps@egroups.com>
> Sent: Monday, June 12, 2000 9:32 PM
> Subject: RE: [noparse][[/noparse]basicstamps] Basic Stamp PLC Style Application Board
>
>
> > What about the noise generated on the AC line due another
machinary
> > near the Stamp. It doesn't affect? How can we avoid the stamp
reset due
> this
> > problem?
> >
> > Alfredo Valles

Archiver

Almost invariably when you hear about problems with Stamps resetting
due to proximity to AC loads being switched it's associated with the
use of mechanical relays. Since they can switch anywhere in the AC
waveform, and their contacts bounce for several milliseconds, they
can be quite potent little wide-spectrum RF noise generators. Solid-
state relays that switch on the zero-crossing of the AC waveform
don't have this problem.

Want to play Mr. Science? Set an AM radio between stations and
position it next to the relay box. Run the relays through their
paces. The noise is amazing. Repeat the experiment with zero-cross-
switching solid-state relays.

----Original quotes:
> I too, have had zero problems with "noise generating a reset" type
of
> problem.
>
> If this is happening to someone they probably have a power supply
> problem.
...and
> > I have a bs2sx mounted 25mm (1 inch) away from a 40Amp solid state
> relay
> > switching a 240 volt ac motor with zero problems ever, outside
noise
> > should'nt be a problem with the reset.
...and
> > > What about the noise generated on the AC line due another
> machinary
> > > near the Stamp. It doesn't affect? How can we avoid the stamp
> reset due
> > this
> > > problem?
> > >
> > > Alfredo Valles

Archiver

That is correct regarding the electro-mechanicl relays and in the industrial
world they are far more common than the more expensive solid state relays.
Also mechanical relays are used because you can have more than one set of
contacts packaged into one relay with a common coil. This is not so easy
with solid state relays. One other matter to consider are motors and their
starters. It is almost non-existant to see a solid state starter for a 60 hp
motor or even for a 10 hp motor. Since the vast majority of motors in
industry are three phase the solid state starters are practically priced out
of existence.

In the real world of industrial machinery noise re-setting ANY type of
microprocessor controlled device is a very big headache. And the only real
solution is proper wiring using twisted pair shielded wiring for the inputs
and proper ground and power planes on the PC cards as well as proper
filtering and isolation of the inputs.

Randy A.

Archiver

In a message dated 6/12/00 10:17:23 AM Central Daylight Time,
stamps@s... writes:

> Almost invariably when you hear about problems with Stamps resetting
> due to proximity to AC loads being switched it's associated with the
> use of mechanical relays. Since they can switch anywhere in the AC
> waveform, and their contacts bounce for several milliseconds, they
> can be quite potent little wide-spectrum RF noise generators. Solid-
> state relays that switch on the zero-crossing of the AC waveform
> don't have this problem.

I've had a few -- just a few -- problems using a Stamp in an industrial
application where a VFD (variable frequency drive) was being used. We've
solved most of the problems by rerouting the wiring to the Stamp and by using
ferrite torroids on the Stamp power supply and other inputs.