Relays: octal vs blade plug-ins?

rklopp · Mar 29, 2017

Is there any reason to prefer octal over blade bases for small plug-in machine tool control relays? The relays I need are available in either flavor base. The dead relays on the machine are not plug-ins, but plug-ins are the modern replacement.

Scottl · Mar 29, 2017

IMO octal stuff is an archaic holdover from the tube days. Blade type are much more readily available and are the standard for automotive and other modestly rated (<50A) relays. Only thing to be careful of is that the socket amperage rating equals or exceeds the relay rating. If you are starting from scratch I highly recommend DIN rail mounted sockets and if the budget will allow it transparent cased relays with indicator LEDs which greatly aid troubleshooting.

rklopp · Mar 29, 2017

Scott
Thank you - very helpful. What about non-socketed relays that mount directly to DIN rail? I need two 3PDT, and I have not seen those in direct mount, so I think would I need six individual relays. Is that correct?

Regards

Rklopp

Monarchist · Mar 29, 2017

rklopp said:
Scott
Thank you - very helpful. What about non-socketed relays that mount directly to DIN rail? I need two 3PDT, and I have not seen those in direct mount, so I think would I need six individual relays. Is that correct?

Regards

Rklopp

Blade - properly done - has better 'wiping' contact and current-carrying capacity that Octal's round pins.

Need 3PDT? Should be out there - 3-Phase. Or use a 4PDT, as for 'starter' apps, leave the latching one spare.

What coil, contact amperage & voltage do you need?

neilho · Mar 29, 2017

To Scott's post, I would add that there's a bigger range of blade type relays available and that the relay/base combinations are cheaper.

SAF · Mar 29, 2017

4 Pole Control Relays

DIN Rail or screw mount 4P, 3NO, 1NC, 10A 120V

Schneider Electric IEC Control Relay, 3NO/1NC, 12VAC, 1A CA2KN31G7 | Zoro.com

And if you need DPDT...
Results for ''

SAF Ω

rklopp · Mar 29, 2017

I need to measure the voltage coming at the coil. The relay says 250V, but there's no 250-V source on the machine. It's a 600-V Canadian machine, and there is a control transformer with 24- and 48-V taps. I have yet to trace which taps are being used to run the relay coil. It could be that I am misreading the contact voltage rating as the coil voltage rating, but there's no other voltage markings. It could also be that under-voltage is what is causing the relay to chatter and fail in the first place.

SAF · Mar 29, 2017

If they are chattering its likely that they have under voltage, check your transformer outputs. Relays are likely good. Also check switching circuits between transformer output and relay coils.

SAF Ω

Monarchist · Mar 29, 2017

rklopp said:
It could be that I am misreading the contact voltage rating as the coil voltage rating,

Highly probable, yes.

Old, old machines usually had only 110/120 VAC for controls, (10EE).

Newer went to 48, newer yet 24.

If in doubt, rip it out.

Re-Engineer for 24. Then you know for sure.

"Old Iron" is worth preserving. Old electricals, much less so.

rklopp · Mar 29, 2017

Wish it were so easy. This Canadian machine is Swiss-made. There are three "alternating" relays labeled 380 V and the apparently bad control relays labeled 250 V. None of that aligns with the OEM 600-V setup sold to Canada. The relays are old fancy-pants Swiss-made devices, so very likely OEM.

The machine uses alternating relays so that the operator pushes the spindle motor button once to start it and again to stop it. Same for the coolant pump and feed motor. There is no separate off switch except two E-stops which shut everything down at once and force a restart of the main control relay.

9100 · Mar 29, 2017

Maybe so, but I replace more blade sockets than octal. Sitting next to my computer right now is an IDEC relay and socket from an eyeleting machine, basically a small punch press that subjects the relay to considerable vibration. You can wiggle the relay and get it to run for a few minutes, then it loses contact on one of the coil blades. I have had that problem with cheap octal sockets but never with good ones. To forestall the question, the relay had the spring on it.

Bill

Monarchist · Mar 29, 2017

rklopp said:
Wish it were so easy. This Canadian machine is Swiss-made. There are three "alternating" relays labeled 380 V and the apparently bad control relays labeled 250 V. None of that aligns with the OEM 600-V setup sold to Canada. The relays are old fancy-pants Swiss-made devices, so very likely OEM.

The machine uses alternating relays so that the operator pushes the spindle motor button once to start it and again to stop it. Same for the coolant pump and feed motor. There is no separate off switch except two E-stops which shut everything down at once and force a restart of the main control relay.

Push start, SAME button push stop?
That's not right. It ain't even a good try at being wrong.

Unsafe.

WTF did they think it was? A reading lamp?

Rip it ALL out then. Do it right. "ON" is on, "OFF" is off.

Paired pushbuttons came into being to side-step that mad Russian Checkist who designed European toggle switches (Colonel Upizoff).

Used to see Marconi made coms gear mounted upside-down in US rackups 'coz it was easier than correcting the wrong sense of the power switches.

But at least it wasn't a dice-roll.

Faster, cheaper, less headache, and it will work as folks expect a machine-tool to work. Prolly need only half as many relays, too..

Jraef · Mar 29, 2017

The only reason socket mounted relays exist is because of old radio tubes, they used the original octal sockets. Blade sockets just evolved when 3PDT relays came out because you could not get enough pins in a round format withoput making the base a lot bigger, then because people liked them better, the mfrs expanded the line down to cover the smaller applications. But they have NEVER been the suggested choice for anything that vibrates.

That's why the other type of relay, as depicted in that photo above, are called "machine tool relays". They are DESIGNED to handle vibration be cause they are intended to be mounted on... wait for it...
.
.
.
machine tools!

jim rozen · Mar 29, 2017

Jraef said:
The only reason socket mounted relays exist is because of old radio tubes, they used the original octal sockets.

Sounds good, except that old radio tubes originally had four pins.
And they never had 11-pin versions, the way relays had.

Monarchist · Mar 29, 2017

jim rozen said:
they never had 11-pin versions, the way relays had.

??

There were plenty of 11-pin Hollow State socketed goods. And more.

Nearly ANY radio that used hollow-state is pretty 'old', and long-since.

9100 · Mar 29, 2017

jim rozen said:
Sounds good, except that old radio tubes originally had four pins.
And they never had 11-pin versions, the way relays had.

Not quite. First they had no pins, just flying leads, then they had screw bases as this spherical deForest Audion in my living room display.

Bill

Edit- I don't know why the picture came out so dark. It was bright in Photoshop.

Ziggy2 · Mar 29, 2017

jim rozen said:
Sounds good, except that old radio tubes originally had four pins.
And they never had 11-pin versions, the way relays had.

The four pin tubes were only diode tubes or a ballast tube. Not many of those in an old radio unless they were making a space heater. The seven pin sockets were much more common in a radio.

A triode tube needed 5 pins and a pentode required 7. There were other combinations also but very few four pin sockets.

rons · Mar 29, 2017

rklopp said:
Is there any reason to prefer octal over blade bases for small plug-in machine tool control relays? The relays I need are available in either flavor base. The dead relays on the machine are not plug-ins, but plug-ins are the modern replacement.

Why don't you drive down to Santa Clara and visit HSC Electronic Supply. Should take about 15 minutes. They have got DIN rail sockets and relays. More than you will ever need. If you like those old AM radios, one of the co-owners is a collector.

rklopp · Mar 29, 2017

Measured voltage to the coil is 50V, so I need a relay with 48-V nominal coil. Those are not so plentiful, although IDEC sells DIN rail SPDT relays with that coil voltage. They are only 6 mm wide.

Monarchist · Mar 30, 2017

Ziggy2 said:
The four pin tubes were only diode tubes or a ballast tube. Not many of those in an old radio unless they were making a space heater.

Actually.. four will do for a Triode. Two for the 'basic', not CT, heater - run off Dee Cee batteries, not AC, in the 'gaslight' days of G'Pa's Atwater-Kent - one each plate and grid.

And then..you forgot the rather common 'cap' lead and we can be into Tetrode's as well - still only a 4-pin base.

My 1938 "AC" (only..) Sparks-Withington's audio amp section ran two 4-pin base 2A3 triodes in class A, AND NOT the class AB1 that my 1947 GE Type 41 ran its 4 push-pull-parallel Octal-base 6V6 beam power pentodes in.

There's still a 'warm spot' in my ....anatomy... for those old 'space heater' hollow-state goods!

Back on topic.

Nominal 48 volt Dee Cee coil relays were all over the telecoms industry for a hundred years and more. Most were for signals switching, only a tiny percentage had the requisite current and voltage ratings, contact side, to control motors and such, but exist they certain do.

Moving a tap, else swapping-out, else simply adding a supplementary control transformer and whatever relay coil needs are handy can be accommodated.

Or even Crydom & Sputnik SSR's, commonly 5 to 35 V, but not-only, at the opto-isolated control side.

Relays: octal vs blade plug-ins?

Diamond

Diamond

Diamond

Diamond

Titanium

Stainless

Diamond

Stainless

Diamond

Diamond

Diamond

Diamond

Titanium

Diamond

Diamond

Diamond

Stainless

Diamond

Diamond

Diamond

Similar threads