power filters

[CptDondo]

I've got a PLC (a little controller) that runs off a generator. The PLC
keeps locking up; we suspect it's due to spikes from the generator.

The PLC only draws a tiny amount of power - less than an amp at 120vac.

Is there an inexpensive filter we can get or build for this thing?

Thanks,

--Yan

 

[Tom Biasi]

I've got a PLC (a little controller) that runs off a generator. The PLC
keeps locking up; we suspect it's due to spikes from the generator.

The PLC only draws a tiny amount of power - less than an amp at 120vac.

Is there an inexpensive filter we can get or build for this thing?

Thanks,

--Yan

Maybe. Filtering keeps something out. Maybe you need something in. Like a
solid sinusoidal 120 VAC.
There could be many things glitching up your PLC.
Specs on the unit and the generator would help.
Tom

 

[Tom Biasi]

Get your self a cheap low power UPS just to operate the PLC.

The cheap, low power UPS may cause him the same problems.

Tom

 

[Jamie]

I've got a PLC (a little controller) that runs off a generator. The PLC
keeps locking up; we suspect it's due to spikes from the generator.

The PLC only draws a tiny amount of power - less than an amp at 120vac.

Is there an inexpensive filter we can get or build for this thing?

Thanks,

--Yan

Get your self a cheap low power UPS just to operate the PLC.

 

[Jamie]

The cheap, low power UPS may cause him the same problems.

Tom

We use industrial mini ups supplies on our PLC's at work, they work
just fine. They are not intended to run the PLC for any length of time,
just produce a nice sine wave 120 V AC . the unit actually shuts off if
it detects constant power loss after a set time on the front panel..
we set ours on most for aprox 1 min. and will restart when power is
returned for at least 1 min .
noise activities and short drop outs can get very erratic and these
things just keep supplying with no problem.

 

[Tom Biasi]

We use industrial mini ups supplies on our PLC's at work, they work
just fine. They are not intended to run the PLC for any length of time,
just produce a nice sine wave 120 V AC . the unit actually shuts off if
it detects constant power loss after a set time on the front panel..
we set ours on most for aprox 1 min. and will restart when power is
returned for at least 1 min .
noise activities and short drop outs can get very erratic and these
things just keep supplying with no problem.

Hey, If they work, Fine.

 

[Michael A. Terrell]

We use industrial mini ups supplies on our PLC's at work, they work
just fine. They are not intended to run the PLC for any length of time,
just produce a nice sine wave 120 V AC . the unit actually shuts off if
it detects constant power loss after a set time on the front panel..
we set ours on most for aprox 1 min. and will restart when power is
returned for at least 1 min .
noise activities and short drop outs can get very erratic and these
things just keep supplying with no problem.

You aren't running them off a small generator that drifts in
frequency. Also, some UPS check the line frequency to make sure the
supply is stable before switching. Unless you are using a very
expensive (And large) online UPS it is still running off the line input,
through a simple LC line frequency filter to remove line noise. Small
and cheap UPS are all off line design, so all you are doing is switching
to battery backup to replace the occasional missing cycles. Read the
documentation of your UPS to see what you are really using.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[zack]

mabe you could use a active power conditioner
transformer type.

 

[CptDondo]

the units we use derive their source from the inverter internally which
is battery back-up. the AC does nothing but keep the battery charged and
supply the inverter.
The cycle change does not effect these units, voltage dips do not
effect these units. I've repaired 2 of these units due to mother nature
whacking our facility. It did nothing but take out the fuse between the
charging circuit and the battery. the battery absorb along with the TVS
units the over surge which force the fuse link to open and also took out
the charging circuit how ever. The unit keeps on operating just fine for
it's preset time before it shuts off.
The charging system is a very simply 60 hz xformer with a bridge, a
couple of resistors, TVS and fuse protection. They're nice little bricks
that sit on the din rail..

Argue all you want, facts are facts.

Do you have a manufacturer / source for these? I'll see if they want to
spring for them....

--Yan

 

[Jamie]

You aren't running them off a small generator that drifts in
frequency. Also, some UPS check the line frequency to make sure the
supply is stable before switching. Unless you are using a very
expensive (And large) online UPS it is still running off the line input,
through a simple LC line frequency filter to remove line noise. Small
and cheap UPS are all off line design, so all you are doing is switching
to battery backup to replace the occasional missing cycles. Read the
documentation of your UPS to see what you are really using.

Let me explain here.
the units we use derive their source from the inverter internally
which is battery back-up. the AC does nothing but keep the battery
charged and supply the inverter.
The cycle change does not effect these units, voltage dips do not
effect these units. I've repaired 2 of these units due to mother nature
whacking our facility. It did nothing but take out the fuse between the
charging circuit and the battery. the battery absorb along with the TVS
units the over surge which force the fuse link to open and also took out
the charging circuit how ever. The unit keeps on operating just fine for
it's preset time before it shuts off.
The charging system is a very simply 60 hz xformer with a bridge, a
couple of resistors, TVS and fuse protection. They're nice little bricks
that sit on the din rail..

Argue all you want, facts are facts.

 

[Michael A. Terrell]

Let me explain here.
the units we use derive their source from the inverter internally
which is battery back-up. the AC does nothing but keep the battery
charged and supply the inverter.
The cycle change does not effect these units, voltage dips do not
effect these units. I've repaired 2 of these units due to mother nature
whacking our facility. It did nothing but take out the fuse between the
charging circuit and the battery. the battery absorb along with the TVS
units the over surge which force the fuse link to open and also took out
the charging circuit how ever. The unit keeps on operating just fine for
it's preset time before it shuts off.
The charging system is a very simply 60 hz xformer with a bridge, a
couple of resistors, TVS and fuse protection. They're nice little bricks
that sit on the din rail..

Argue all you want, facts are facts.

So, these don't even try to match the line frequency or phase before
they switch over? What a nasty design.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[CptDondo]

So, these don't even try to match the line frequency or phase before
they switch over? What a nasty design.

I think you're missing the point. If I understand this correctly, there
is no "switch".

The "UPS" takes AC to DC, charges a battery. Then there is an inverter
that takes DC from the battery and provides AC.

There is no AC - AC connection or switch; the unit is *always* fed from
the inverter, and *never* from the grid.

--Yan

 

[Michael A. Terrell]

I think you're missing the point. If I understand this correctly, there
is no "switch".

Sorry, but you don't understand.

The "UPS" takes AC to DC, charges a battery. Then there is an inverter
that takes DC from the battery and provides AC.

You are missing the point. There are TWO types of UPS. Off line and
on line. Small UPS systems are typically off line type, where they do
switch the inverter on and connect it to the load when there is a
problem.

There is no AC - AC connection or switch; the unit is *always* fed from
the inverter, and *never* from the grid.

Only in 'on line' UPS systemms. BTW, the smallest online UPS I've
seen was 15 KW. Even then, there were manual switches to bypass the
system, for maintanence.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Michael A. Terrell]

I think you're missing the point. If I understand this correctly, there
is no "switch".

http://en.wikipedia.org/wiki/Uninterruptible_power_supply has a very
simplified explaination of most types of UPS.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[CptDondo]

Only in 'on line' UPS systemms. BTW, the smallest online UPS I've
seen was 15 KW. Even then, there were manual switches to bypass the
system, for maintanence.

A bit of googling will find them as small as 500va.

 

[Jamie]

I think you're missing the point. If I understand this correctly, there
is no "switch".

The "UPS" takes AC to DC, charges a battery. Then there is an inverter
that takes DC from the battery and provides AC.

There is no AC - AC connection or switch; the unit is *always* fed from
the inverter, and *never* from the grid.

--Yan

I'm glad some one understands it.

 

[Jamie]

So, these don't even try to match the line frequency or phase before
they switch over? What a nasty design.

No , they don't match the line freq. the output is from the inverter at
all times. the inverter is operating from a DC supply which is the
battery which gets charged from the line..
Our units we use have an option to turn off after a set time when the
UPS has determine that line voltage is absent and not just being
erratic. We do this to prevent some sensitive systems like PLC's,UC etc,
to shut down and restart properly when power is lost.
The one we use for our Wonderware is connected to the serial port to
instruct it to shut down so that windows is properly terminated before
it losses power.

 

[Michael A. Terrell]

A bit of googling will find them as small as 500va.

At what price and efficiency?


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Michael A. Terrell]

No , they don't match the line freq. the output is from the inverter at
all times. the inverter is operating from a DC supply which is the
battery which gets charged from the line..

That can cause problems with some equipment but if you want to use
junk, feel free.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Michael A. Terrell]

Ah yes, of course, the batteries. APC makes a good standby UPS, but expect
to change its battery every three years, and that's not terribly cheap.
Two years ago I hired on at a new company. One of my first engineering
decisions involved an UPS. The technician wanted to throw out a small APC
unit when it stopped functioning correctly. I asked him when was the last
time he changed the battery. He replied, "Battery?" Not that he was a bad
tech, he just had a limited knowledge base.

My first APC last for over five years on the OEM battery. Sine then,
I've had so many given to me that I haven't needed to buy batteries in
over 10 year. Yes, the batteries do fail, especially when the electric
goes out often, and the computer isn't set up to shut down.

Right now I have at least 12 spares with usable batteries, and I could
probably get several hundred more per year, for free. Replacement
batteries aren't that bad, bought in bulk. APC is very high, compared
to OEM and surplus sources. I used to pick up used Gates battery packs
from a Diebold repair center, and sell them to amateur radio operators
for standby power. they still bug me for more cheap batteries, but the
source is gone. I also have several new 17 AH 12 VDC gel cells from
those portable starter packs for cars. I'm tempted to use them as
external batteries on a pair of old 1000 VA APC UPS I have in storage
for my server and web design computers. The 650 VA APC can't handle the
computer and HP 1130 monitor, and odds and ends in my office.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida