Eng-Tips is the largest engineering community on the Internet
Intelligent Work Forums for Engineering Professionals
Solenoid rated 24v 60hz supplied with 24vdc
- Thread starter fivecents
- Start date
No. It is likely to start smoking badly in about.... 2 seconds.
AC solenoids control the current thru themselves by their inductance, of course DC doesn't care about inductance and would run unchecked thru the windings.
DC solenoids are wound to have their wire resistance limit the current.
Keith Cress
kcress -
AC solenoids control the current thru themselves by their inductance, of course DC doesn't care about inductance and would run unchecked thru the windings.
DC solenoids are wound to have their wire resistance limit the current.
Keith Cress
kcress -
Skogsgurra
Electrical
They may live a little bit longer in the Nordic countries. Think three seconds instead of two.
But it may be possible to use them also on DC. Keith has tried that technique once without remembering it. Use a large capacitor and charge it via a resistor. Pull in the solenoid by connecting the charged capacitor across the solenoid. You will need to experiment with capacitor value, start at 1000 microfarad and don't be surprised if you need a lot more than that.
When the solenoid pulls in, you need to adjust the resistor so you get a safe seal-in current. It will probably be in the order of 10 - 20 percent of the pull in current. Contactors with a drop-out delay are built like that. Usually with an NC contact that bridges the resistor during pull-in.
Gunnar Englund
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
But it may be possible to use them also on DC. Keith has tried that technique once without remembering it. Use a large capacitor and charge it via a resistor. Pull in the solenoid by connecting the charged capacitor across the solenoid. You will need to experiment with capacitor value, start at 1000 microfarad and don't be surprised if you need a lot more than that.
When the solenoid pulls in, you need to adjust the resistor so you get a safe seal-in current. It will probably be in the order of 10 - 20 percent of the pull in current. Contactors with a drop-out delay are built like that. Usually with an NC contact that bridges the resistor during pull-in.
Gunnar Englund
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
I need Gunnar as a memory element! Too frequently I start troubleshooting something only to remember, 'I've had this exact problem with this $#*^ device before..'
fivecents; Depending on your situation there is also a standard turn-down method where you can use a higher voltage AC relay successfully with low voltage DC. In this case the many winds used in the higher voltage AC unit provide enough DC resistance to allow the lower voltage to work acceptably. It's something like a 120VAC unit can be run with 24VDC, or is it 240VAC->24VDC and 120VAC->12VDC.?.
Here's a link that discusses it in detail:
[URL unfurl="true"]http://ecmweb.com/content/using-ac-coils-dc-power[/url]
Keith Cress
kcress -
fivecents; Depending on your situation there is also a standard turn-down method where you can use a higher voltage AC relay successfully with low voltage DC. In this case the many winds used in the higher voltage AC unit provide enough DC resistance to allow the lower voltage to work acceptably. It's something like a 120VAC unit can be run with 24VDC, or is it 240VAC->24VDC and 120VAC->12VDC.?.
Here's a link that discusses it in detail:
[URL unfurl="true"]http://ecmweb.com/content/using-ac-coils-dc-power[/url]
Keith Cress
kcress -
Skogsgurra
Electrical
Don't be such a bore! We simple minds need simple distractions. AC or DC? - that makes us tick for hours...
But, of course, you are right. I just didn't think that it was possible. If it is, then so much better.
Gunnar Englund
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
But, of course, you are right. I just didn't think that it was possible. If it is, then so much better.
Gunnar Englund
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
It depends on the solenoid. Some AC solenoid valves have DC-wound coils fitted with an integral bridge rectifier. These ones usually work fine on DC. Why make them that way? I think it's probably to make them less prone to burning out if the valve fails to pull in properly when energised (either because the spool is stuck, the voltage on the energising supply has drooped, or somebody has dismounted the coil from the valve as a quick diagnostic bodge).
How do you tell what sort of coil you've working with?
1. Read the bumf.
2. Connect to DC and measure MTTFPS (mean time to first puff...)
3. Try measuring coil resistance using a 1.2 V cell and an ammeter. If the cell fails to push any reasonable current through the coil, that suggests either that you've already failed test (2) above, or that the cell is facing a couple of diode forward voltage drops.
A.
How do you tell what sort of coil you've working with?
1. Read the bumf.
2. Connect to DC and measure MTTFPS (mean time to first puff...)
3. Try measuring coil resistance using a 1.2 V cell and an ammeter. If the cell fails to push any reasonable current through the coil, that suggests either that you've already failed test (2) above, or that the cell is facing a couple of diode forward voltage drops.
A.
I just spent 2 hours talking someone into using a VFD to be able to run his 460V 3 phase motor from a 240V single phase source, it will cost him about $3000 US to get it all done when you factor in the transformer necessary and labor to hook it all up. A half hour later it dawned on me to look up a price on a 240V single phase motor with the same frame size, $2000... oops...
"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington
"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington
- Thread starter
- #9
"MTTFPS" I love new acronyms. That being said the scenario was old machine(from ebay,craigslist or maybe Freedonia) had solenoid failure. A spare on the shelf, unfortunately the spare was 24ac and the supply was 24vdc.
Upon further investigation 2 other solenoids on machine junk.. New solenoids with 24vdc rated coils coming soon.
Upon further investigation 2 other solenoids on machine junk.. New solenoids with 24vdc rated coils coming soon.
The simple rule of thumb I follow is if you have an unknown solenoid, test it on AC first. Worst case, the winding impedance will be too high and the coil will likely fail to pull or else will buzz severely as the armature vibrates during each zero crossing, and then you know it's DC.
If you try it in reverse and apply full DC to an AC rated coil then the winding resistance can be far too low to oppose pure direct current and you'll end up smoking the coil.
If you try it in reverse and apply full DC to an AC rated coil then the winding resistance can be far too low to oppose pure direct current and you'll end up smoking the coil.
I have had one case where a 120 volt AC relay worked on 24V DC. That was for a short time. The problem was when power was removed and the relay was supposed to have opened. It didn't, The Iron path had permanently magnetize.
125 and 250 volt DC relays have springs like bear traps and many have parallel coils. The "holding" part of the coil has more turns and higher resistance.
125 and 250 volt DC relays have springs like bear traps and many have parallel coils. The "holding" part of the coil has more turns and higher resistance.
Skogsgurra
Electrical
In an emergency, you could add .1 or .2 m brass shim between core and armature. That usuallly makes it drop out when DC goes to zero.
Gunnar Englund
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
Gunnar Englund
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
- Status
Similar threads
- Question
- Locked
- Question
- Locked
- Question