SSR switching HT transformer? - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 1st March 2013, 08:03 PM   #1
Matt BH is offline Matt BH  United Kingdom
diyAudio Member
 
Join Date: Jul 2009
Location: Cheltenham
Default SSR switching HT transformer?

Hello, I have been thinking about using an SSR to switch the primary of my GM70 projects HT transformer. I have just noticed in MJs latest book that he says he is not sure about this because of problems during the zero crossing (page 415 "the switch-on surge")

Has anyone had any problems using an SSR or other triac/dual SCR type switching device in an amp?

Also I always thought that switch on surge was greatest if you switch on at the zero point because the waveform is rising in which ever direction and the current very rapidly increases to the peak dictated by wiring impedance etc. Morgan Jones states it is at the peak on either side of zero but I can see the current only going down from this point.

Cheers

Matt.

Last edited by Matt BH; 1st March 2013 at 08:23 PM. Reason: triac doh.
  Reply With Quote
Old 1st March 2013, 09:15 PM   #2
diyAudio Member
 
Rundmaus's Avatar
 
Join Date: Aug 2005
If you switch at zero voltage, the voltage across the primary and the primary current rise with the sinusoidal waveform of the mains.

Switching on at any other instant applies a large voltage across the primary *instantly*, leading to a switch-on surge.

So switching at the zero crossing of the mains is best. You can get SSR that automatically detect the zero crossing and switch then, usually they are only slightly more expensive than the randomly switching ones. Worth the money.

Regards,
Andreas
  Reply With Quote
Old 1st March 2013, 09:23 PM   #3
diyAudio Member
 
Join Date: Dec 2012
Location: The Jurassic Coast, England. GB
Send a message via Skype™ to JonSnell Electronic
Major manufacturers utilize a soft start relay and a high wattage 22R in series with the primary. When the mains is applied the 22R series resistor limits the current and a simple RC timer turns the relay on shorting out the resistor.
Very successful on high powered amplifiers and cheap!
  Reply With Quote
Old 1st March 2013, 09:50 PM   #4
diyAudio Member
 
Join Date: Jun 2011
Quote:
Originally Posted by Matt.B.H. View Post
Hello, I have been thinking about using an SSR to switch the primary of my GM70 projects HT transformer. I have just noticed in MJs latest book that he says he is not sure about this because of problems during the zero crossing (page 415 "the switch-on surge")
How is that different from randomly throwing a switch?
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Selah Audio SSR kit, NEW in Box! sbrtoy Swap Meet 2 11th October 2012 04:54 PM
SSR derating tvrgeek Parts 6 13th March 2012 08:31 PM
Power transformer HT/B+ voltages vivid Tubes / Valves 20 2nd July 2009 10:32 PM
12dc ssr for chip amp problem DeanP Chip Amps 2 25th October 2006 01:58 PM


New To Site? Need Help?

All times are GMT. The time now is 12:50 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2