Pages: [1] 2   Go Down

Author Topic: Line voltage surge protection  (Read 639 times)

K7MPZ

  • Member
  • Posts: 129
Line voltage surge protection
« on: May 25, 2021, 05:33:00 PM »

I have six mission critical radios, and various accessories, all running on 12 volts from a not very well regulated ac/dc switching supply.  I am considering stepping up to a linear type supply for more capacity, and potentially some isolation from
terribly frequent voltage spikes.  My questions are:
will the transformer type power supply help at all?
what device will help?
I have started looking on my own, but nothing beats the wisdom of those who gone before me.
Logged
Dale Fiorillo
Sequim, Wa
K7MPZ

K6AER

  • Member
  • Posts: 7159
Re: Line voltage surge protection
« Reply #1 on: May 25, 2021, 06:08:58 PM »

It doesn't matter wither the power supply has a transformer or a isolated toroid. When tihe AC voltage rises to a potential looking for a ground you have a surge event. Power poles can limit the surge to 10-15 KV but that is still to high for radios and power supplies to survive. The only real solution is a commercial surge protector on the main AC feed.

Next in line is a very low impedance ground with all AC grounds bonded to the main grounding rod. The deeper the ground rod the better. I would have at least a 20 foot ground rod. Do not trust the one at the panel for it may be compromised just below the surface.

Most damage from lightning strikes comes in via the AC panel. As for the antennas, I would use a grounded antenna selector switch. The good news is in your part of the country there is little lightning.
Logged

K7MPZ

  • Member
  • Posts: 129
Re: Line voltage surge protection
« Reply #2 on: May 25, 2021, 08:15:04 PM »

I spent the last few hours researching this, learned some, confused on some.  I am not concerned with lightning, it's just line voltage spikes. Not convinced I even want a ups, would be nice to keep the radios running, but keeping them from a deadly spike is far more imp0rtant. 
What do you know about using a 1:1 line transformer?  I had a variac many years ago, but only used it set the line
voltage.
Logged
Dale Fiorillo
Sequim, Wa
K7MPZ

W9FIB

  • Member
  • Posts: 3501
    • HomeURL
Re: Line voltage surge protection
« Reply #3 on: May 26, 2021, 03:14:34 AM »

Think about it this way...If you have a transformer that takes an input of 120VAC and output is 12VAC and increase the input voltage, the output voltage will also rise. Not much protection, but some due to internal impedance and the spike being short lived.

In the case of a high voltage spike, best protection is to use MOVs (Metal Oxide Varistors) to eliminate the spike. I use them both on the AC mains coming into the supply and at the DC output of the supply. MOVs are usually what are in many power strips with lightning protection.

Also the power supply should have a quality crowbar circuit to blow the fuse should the DC output rise too high.
Logged
73, Stan
Travelling the world one signal at a time.

W9IQ

  • Member
  • Posts: 8866
Re: Line voltage surge protection
« Reply #4 on: May 26, 2021, 05:32:23 AM »

After you do everything you technically can to protect your equipment, the next best thing is insurance to reimburse you if damage does occur. The best "free" insurance I have found is to buy the one to three outlet Tripp-Lite "Spike Cube". It comes with "$5,000 Ultimate Lifetime Insurance". Read the policy requirements - they look quite reasonable. I have never had to file a claim so I cannot speak to their honor.

If you need multiple outlet protection, the Tripp-Lite Iso-Bar line is highly regarded and a four outlet strip carries a $50,000 policy.

- Glenn W9IQ
Logged
- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

W9IQ

  • Member
  • Posts: 8866
Re: Line voltage surge protection
« Reply #5 on: May 26, 2021, 05:34:25 AM »

For general recommendations for a power supply, it would be necessary to know what maximum amperage you require. Do you need the capability to switch over to battery power if the AC fails?

- Glenn W9IQ
Logged
- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

K7MPZ

  • Member
  • Posts: 129
Re: Line voltage surge protection
« Reply #6 on: May 26, 2021, 01:51:06 PM »

Glen, I am using an Alinco DM-430T, 30Amp, switching. It runs hot with 5 radios running,
digital messaging, ssb, and vhf/uhf FM transmitting.
I am ready to buy the Astron 35M.  It has way better specs, and a crowbar circuit.
If the ac power goes off I have a large backup battery system.
What I want to accomplish is reducing the potential damage from AC line voltage
spikes when the power returns.
I keep thinking of a relay that would open if its primary were interupted
You asked about max amperage, so I just now keyed all the radios on high power, and
saw a drain of 25 amps, but the voltage dropped .3vdc, and the hf transceiver rebooted! 
Logged
Dale Fiorillo
Sequim, Wa
K7MPZ

W9IQ

  • Member
  • Posts: 8866
Re: Line voltage surge protection
« Reply #7 on: May 26, 2021, 02:06:28 PM »

Do be cautious with the Astron specs. Their model number is actually the peak amps - continuous amps are less. So shop carefully.

You may want to pull the spec sheets for your radios to add up the maximum potential current draw. Or whatever the realistic simultaneous draw situation is for your use case. I would then oversize the supply by at least 20% - more would be better.

Most supplies will do a good job of regulating out the normal power line spikes and sags but won't do much for lightning induced type surges. That is where a good surge arrestor such as the Tripp-Lite type I referenced early come in. You can also install a "whole house" version at your breaker panel.

- Glenn W9IQ
Logged
- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

K7MPZ

  • Member
  • Posts: 129
Re: Line voltage surge protection
« Reply #8 on: May 26, 2021, 03:00:29 PM »

Thanks for all the advice. I will have some details for the electrician doing my new house!  It
looks like a Tripp-lite product will solve the non-lightning spikes, and a bigger ac/dc supply
will allow the smaller ps to go to a go-kit.
I just posted in the Misc. section a question about the total dropout of line voltage, and
the return of unregulated power.My neighborhood is new, and growing, so we have many
power interruptions while the electricians do their thing. What I want is a way to stop the
power from returning to the radios when I can't get to the safety switch in time. So, hopefully
there is a way to utilize a latching/unlatching relay for this purpose.  I have worked with
many relays, but never a latching type.  I spent an hour online, but did not see what I think
I want!
Logged
Dale Fiorillo
Sequim, Wa
K7MPZ

AA4PB

  • Member
  • Posts: 15504
Re: Line voltage surge protection
« Reply #9 on: May 26, 2021, 04:03:44 PM »

You don't need a latching relay to do what you want. All you need is a standard relay with a 120VAC coil. Wire the relay contacts to supply power to your equipment *and* supply power to the relay coil. When the relay is closed it will supply power to the coil and keep the contacts closed. If power is interrupted then the relay will open and remain open until you reset it by momentarily bypassing the contacts.
 
Logged
Bob  AA4PB
Garrisonville, VA

K7MPZ

  • Member
  • Posts: 129
Re: Line voltage surge protection
« Reply #10 on: May 26, 2021, 04:49:40 PM »

Hey Bob it was simple, now to build it.  i kept trying to make it complicated.
Logged
Dale Fiorillo
Sequim, Wa
K7MPZ

WB4SPT

  • Member
  • Posts: 917
Re: Line voltage surge protection
« Reply #11 on: November 05, 2021, 10:19:37 AM »

I spent the last few hours researching this....
What do you know about using a 1:1 line transformer?  I had a variac many years ago, but only used it set the line
voltage.

You might want to study DM vs CM surge events.   An isolation transformer (NOT a variac), does  a great job stomping on CM surge events.   Mostly removes them.   DM is best killed with MOV's across the line.  They are fast, but they do have their limits.  My work/world is concerned with keeping substation electronics working, during some pretty high level "events".   We use terms like "switching surge", "lightning surge", slow oscillatory, fast oscillatory, EFT, dips, interrups,... you get the idea.  I'm not sure about the threats you speak of, but agree that HV distribution switching does cause transients. 
Logged

ZL1BBW

  • Member
  • Posts: 1914
Re: Line voltage surge protection
« Reply #12 on: November 05, 2021, 06:05:04 PM »

What about a Constant Voltage Transformer?  used one many years ago.   https://www.aelgroup.co.uk/faq/faq001.php
Logged
ex MN Radio Officer, Portishead Radio GKA, BT Radio Amateur Morse Tester.  Licensed as G3YCP ZL1DAB, now taken over my father (sk) call as ZL1BBW.

W3KHQ

  • Member
  • Posts: 6
Re: Line voltage surge protection
« Reply #13 on: November 05, 2021, 07:16:41 PM »

How about using a  SOLA Constant Voltage A.C. Supply. Not cheap, but will give you good protection.

Harold W3KHQ
Logged

N8FVJ

  • Member
  • Posts: 1270
Re: Line voltage surge protection
« Reply #14 on: December 22, 2021, 03:49:12 PM »

Most power supplies have an internal MOV device to limit 120 volt AC surges.
Logged
Pages: [1] 2   Go Up