High Voltage and Static Questions
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Posts: 46,084
As always you guys and gals in here have some pretty good
information....thanks
Anyway, I have a two part question.
1)
How far away should the stamp be located from a relay that switches
high voltage circuits? Is there the possibility of some form of
disturbance in the watchdog circuit of the stamp if near high current
circuits switching on or off? The reason I ask this is because I have
to control a machine that has a 3/4 hp motor. When the relay closes or
opens SOMETIMES I get strange behavior from the stamp and I find the
stamps usually freezes, re-starts the program from the begining and
sometimes I lose needed data because the WRITE routines in my program
never get a chance to execute. Right now the relay is mounted on the
PCB next to the stamp. Could this be a cause of my problem?
2)
This same circuit has a metal key panel that has momentary key
switches in it. I notice when it is very cold and dry there is static
build up and if you touch the key panel while passing you can induce a
watchdog reset by means of eletrostatic discharge thru the keyswitches
to the stamp. The metal casing of the switch is isolated from the
contacts but I imagine the static is arcing internally thru the switch
contacts. I was thinking of grounding the key panel. Should I ground
it to the earth wire on the mainframe of the machine or should I
ground it to the negative side of the low voltage power supply? I only
ask this because I have been told that the earth of a machine could be
noisy and induce problems.
information....thanks
Anyway, I have a two part question.
1)
How far away should the stamp be located from a relay that switches
high voltage circuits? Is there the possibility of some form of
disturbance in the watchdog circuit of the stamp if near high current
circuits switching on or off? The reason I ask this is because I have
to control a machine that has a 3/4 hp motor. When the relay closes or
opens SOMETIMES I get strange behavior from the stamp and I find the
stamps usually freezes, re-starts the program from the begining and
sometimes I lose needed data because the WRITE routines in my program
never get a chance to execute. Right now the relay is mounted on the
PCB next to the stamp. Could this be a cause of my problem?
2)
This same circuit has a metal key panel that has momentary key
switches in it. I notice when it is very cold and dry there is static
build up and if you touch the key panel while passing you can induce a
watchdog reset by means of eletrostatic discharge thru the keyswitches
to the stamp. The metal casing of the switch is isolated from the
contacts but I imagine the static is arcing internally thru the switch
contacts. I was thinking of grounding the key panel. Should I ground
it to the earth wire on the mainframe of the machine or should I
ground it to the negative side of the low voltage power supply? I only
ask this because I have been told that the earth of a machine could be
noisy and induce problems.
Comments
to mind is to use Opto-isolators on all stamp I/O. This would require separate
power supplies for the stamp and the "other" circuit to stay truely isolated.
In a message dated 12/30/2003 5:37:53 PM Pacific Standard Time,
generatorlabs@y... writes:
As always you guys and gals in here have some pretty good
information....thanks
Anyway, I have a two part question.
1)
How far away should the stamp be located from a relay that switches
high voltage circuits? Is there the possibility of some form of
disturbance in the watchdog circuit of the stamp if near high current
circuits switching on or off? The reason I ask this is because I have
to control a machine that has a 3/4 hp motor. When the relay closes or
opens SOMETIMES I get strange behavior from the stamp and I find the
stamps usually freezes, re-starts the program from the begining and
sometimes I lose needed data because the WRITE routines in my program
never get a chance to execute. Right now the relay is mounted on the
PCB next to the stamp. Could this be a cause of my problem?
2)
This same circuit has a metal key panel that has momentary key
switches in it. I notice when it is very cold and dry there is static
build up and if you touch the key panel while passing you can induce a
watchdog reset by means of eletrostatic discharge thru the keyswitches
to the stamp. The metal casing of the switch is isolated from the
contacts but I imagine the static is arcing internally thru the switch
contacts. I was thinking of grounding the key panel. Should I ground
it to the earth wire on the mainframe of the machine or should I
ground it to the negative side of the low voltage power supply? I only
ask this because I have been told that the earth of a machine could be
noisy and induce problems.
[noparse][[/noparse]Non-text portions of this message have been removed]
Are you using 120/2020 single phase AC or 3 Phase 480 Volt AC motors?
I routinely control large contactors with a Stamp. I use Opto isolators,
solid state relays(SSR's), and Digital Noise Filters on all I/O and Power to the
Stamp. I use one weather the pin is used or not.
I Use a Murata-Erie part number 81-DSS306-55Y5S471M100. I get them from
Mouser Electronics. They cost about a buck a piece, but are worth their weight
in
gold. They look like a 3 legged capacitor. the signal goes through the outside
legs and the center leg is grounded. Try to ground them as close to the
central ground point as possible. I put one on all 16 I/O pins, the 3 Serial
pins
(1,2,3), reset pin and the +5 input. Also remember to unplug the programming
cable when running the circuit. I have had problems when this is left plugged in
while running a Plasma Cutting Machine. This starts with a controlled
Lightning Bolt to fire a cutting torch. About 10 kV at 2 MHz. With the cable
unplugged
there is no problem.
I would put the relay as far away as possible. I usually have the SSR's
mounted on the PC board and the motor contactors mounded off the board. 6 inches
should be far enough.
If you are laying out a PC board make the ground traces as big as possible
and try to avoid any loops in the run.
The Opto isolator and/or solid state relay will also help by keeping the
relay power separate from the stamp power. I use AC solid state relays to drive
AC
Coil Relays. I have driven the main contactor of a 200 KW DC power supply in
this fashion. (It is much easier than it sounds, but has allot of dramatic
effect!)
I hope this helps, if not give another shout.
Alan Bradford
Plasma Technologies
www.plasmatechnologies.com
In a message dated 12/30/03 8:37:46 PM Eastern Standard Time,
generatorlabs@y... writes:
As always you guys and gals in here have some pretty good
information....thanks
Anyway, I have a two part question.
1)
How far away should the stamp be located from a relay that switches
high voltage circuits? Is there the possibility of some form of
disturbance in the watchdog circuit of the stamp if near high current
circuits switching on or off? The reason I ask this is because I have
to control a machine that has a 3/4 hp motor. When the relay closes or
opens SOMETIMES I get strange behavior from the stamp and I find the
stamps usually freezes, re-starts the program from the begining and
sometimes I lose needed data because the WRITE routines in my program
never get a chance to execute. Right now the relay is mounted on the
PCB next to the stamp. Could this be a cause of my problem?
2)
This same circuit has a metal key panel that has momentary key
switches in it. I notice when it is very cold and dry there is static
build up and if you touch the key panel while passing you can induce a
watchdog reset by means of eletrostatic discharge thru the keyswitches
to the stamp. The metal casing of the switch is isolated from the
contacts but I imagine the static is arcing internally thru the switch
contacts. I was thinking of grounding the key panel. Should I ground
it to the earth wire on the mainframe of the machine or should I
ground it to the negative side of the low voltage power supply? I only
ask this because I have been told that the earth of a machine could be
noisy and induce problems.
[noparse][[/noparse]Non-text portions of this message have been removed]
>Mouser Electronics. They cost about a buck a piece, but are worth their
>weight in gold.
Alan,
I did a search on the part number above on mouser.com but didn't find
anything; do you have a mouser (or digikey) part number?
Thanks,
-John
You should have better luck,
EJ
Original Message
From: "John Walton" <john@l...>
To: <basicstamps@yahoogroups.com>
Sent: Wednesday, December 31, 2003 10:21 PM
Subject: RE: [noparse][[/noparse]basicstamps] High Voltage and Static Questions
>
> >I Use a Murata-Erie part number 81-DSS306-55Y5S471M100. I get them from
>
> >Mouser Electronics. They cost about a buck a piece, but are worth their
> >weight in gold.
>
> Alan,
>
> I did a search on the part number above on mouser.com but didn't find
> anything; do you have a mouser (or digikey) part number?
>
> Thanks,
>
> -John
>
>
>
>
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This is what I have in my database.
Murata-Erie Part Number DSS306-55Y5S471M100
Mouser Part Number 81-DSS306Y5S471M1
Here is the link to the catalog.
http://www.mouser.com/catalog/616/530.pdf
I was trying to type the number too fast yesterday and got a few digits mixed
up! I cut and pasted them today.
Happy New Year
Alan Bradford
Plasma Technologies
In a message dated 1/1/2004 1:25:22 AM Eastern Standard Time,
john@l... writes:
>I Use a Murata-Erie part number 81-DSS306-55Y5S471M100. I get them from
>Mouser Electronics. They cost about a buck a piece, but are worth their
>weight in gold.
Alan,
I did a search on the part number above on mouser.com but didn't find
anything; do you have a mouser (or digikey) part number?
Thanks,
[noparse][[/noparse]Non-text portions of this message have been removed]
voltage circuits? Is there the possibility of some form of disturbance in
the watchdog circuit of the stamp if near high current circuits switching on
or off? The reason I ask this is because I have
to control a machine that has a 3/4 hp motor. When the relay closes or opens
SOMETIMES I get strange behavior from the stamp and I find the stamps
usually freezes, re-starts the program from the begining ...
In some early experiments, I found that the current drain of closing a
relay, pulled enough power away from the rest of the circuit that the BS2
detected it as a power low condition, and rebooted. Now I routinely set up a
second power supply to drive relays and coils, and put 100 ohm resistors in
series with relay coils, as well as the usual diodes. Separate power
supplies solve a lot of problems.