I need help on Hydraulic Solenoid Coils

[ndzied1]

Bud,

Maybe something like this :
http://www.axiomatic.com/hot-shot-coil-saver.html
can help hold the heating of the valve down?

 

[CaseyK]

Going back to 1975, when I left controls engineering to go be an electrician (Why did I go and do that?), I found that in the cannery, the 120 volt ac coils were the most trouble free. We had some low voltage, 120, 208, 240, and 480. Over the years, I noticed this was generally the case everywhere. No rhyme or reason for it. It still takes the same amount of power (watts) to hold in the plunger, and watts translates to heat.

 

[Jasonc24]

Gentlemen:

Not to contradict anyone out there, however I was of a different impression regarding the relationship between voltage, current, and temperature.

Heat, I had always thought, was the direct result of current through a conductor, not power. For example, we fuse a conductor for a specific current so that it does not heat up and cause a fire. If we have a 10A rated conductor, it makes no difference whether the source voltage is 24VDC or 480VAC, either way anything more than 10A will cause the conductor to heat up.

As for the coil on your solenoid valve, meat burning" heat that you refer to is typically caused by the electrical characteristics of the coil itself, not the fluid passing. A good way to determine the difference, however, is to feel the actual valve body near the spool. If that is hotter than the coil, then the temperature is coming from the fluid. It the coil is hotter, then the temperature is coming from the coil.

This type of high temperature, although undesirable, is not unusual. There is no harm done (unless you touch it) to the system by having this hot of a coil. I have many 24VDC coils in the field that run as hot as you describe (in the neighborhood of several thousand), and coil failures are very rare. If desired, however, try switching to a 120VAC coil and that should solve the problem.

 

[hd_coop]

Gentlemen:

Not to contradict anyone out there, however I was of a different impression regarding the relationship between voltage, current, and temperature.

Heat, I had always thought, was the direct result of current through a conductor, not power. For example, we fuse a conductor for a specific current so that it does not heat up and cause a fire. If we have a 10A rated conductor, it makes no difference whether the source voltage is 24VDC or 480VAC, either way anything more than 10A will cause the conductor to heat up.

I am pretty sure heat is a resultant of power, not current. The reason a fuse doesn't care what the source voltage is because P = I^2*R, and R is constant.

 

[rsdoran]

Ever buy a small electric heater? How is it rated? Watts is the "rate" of power (work) that is moved or transformed. Voltage is the "force", current is the "electron flow" and watts are the rate the energy provided is consumed. With a coil using 40 watts of energy, hopefully most of that is used doing the mechanical "work" but lets say its usin the 40 watts but something is causing it to draw excess current which will expend 60 watts, that extra 20 watts will be converted to "heat". In general that does not sound like much but how many of you have used a 15, 25, ...watt soldering iron?

If the coil gets "too" hot and its not due to fluid temperature then you may have another issue.

hd a fuse does care what voltage is provided, there is a relationship. That is a common mistake many maintenance personnel make when changing fuses.

 

[Leadfoot]

Power is expressed in WATTS. Heat is also expressed in WATTS.

Both are related, both are seperate.

If you have 24 volts and 1 amp you have 24 watts of energy. NOT all of this is coverted to heat. Some is doing useful WORK.

746 watts of electrical energy is equal to 1 horsepower.

The heat build up on electrical components is due to the current times resistance losses. I squared R losses or watt losses and this is what makes the component gain heat. The temperature rise spec is related to the watt loss of the component.

A 7 watt night light bulb will blister your skin. A coil at 120 volts ac and 0.25 amps is 30 watts. This is more than 4 times the night light bulb and will definately blister your skin and cause pain.

edit

RS,

Looks like we were both typing along the same idea together.

 

[rsdoran]

Who has trivia????

Just to throw some trivia out there:

Operating a "cooling" fan in a closed room heats up the room at a rate equal to the voltage times electrical current going into the fan...example: 120 volts x 2 amps = 240 watts of heat

An average 150 pound person generates 93 watts of heat while sleeping.

 

[Leadfoot]

Just to throw some trivia out there:


An average 150 pound person generates 93 watts of heat while sleeping.

I know a few persons that generate a bunch more heat when they speak.

It is a good thing some of us on this board are not in the same room, myself included. LOL.

 

[hd_coop]

hd a fuse does care what voltage is provided, there is a relationship. That is a common mistake many maintenance personnel make when changing fuses.

Are you saying a 5A fuse will care whether it is protecting a 24VDC line versus or 120VAC line, or are you simply referring to the maximum ratings?
For example, we use a lot of Bussman LP-CC-xx fuses which are rated at 150 or 300 VDC (depending on size) or 600VAC....would the fuse care if it had 24VDC or 120VAC? Or is it just if you exceed the voltage ratings of the fuse?

 

[rsdoran]

Are you saying a 5A fuse will care whether it is protecting a 24VDC line versus or 120VAC line, or are you simply referring to the maximum ratings?

It can, a fuse rated 32vdc doesnt work well on a 120vac ckt. The fuse would care if the voltage rating is exceeded, the relationship is lost.

You can go to Bussman, Littlefuse etc and check it out, fuses are designed using the relationship between current, resistance, and heat. If the voltage value increases then the relationship has changed.

 

[hd_coop]

It can, a fuse rated 32vdc doesnt work well on a 120vac ckt. The fuse would care if the voltage rating is exceeded, the relationship is lost.

You can go to Bussman, Littlefuse etc and check it out, fuses are designed using the relationship between current, resistance, and heat. If the voltage value increases then the relationship has changed.

The fuse I gave an example of with a rating of 300VDC or 600VAC would not care though because the voltage rating has not been exceeded, correct?

 

[rsdoran]

hd I feel like I am being the Devil's Advocate or something, I dont want to be that.

In the construction of fuses they use a relationship between a specific voltage range, current and heat. If you use a 600vdc fuse on a 12vdc ckt do you think the relationship is maintained? In general it may work but it will never work properly.

I am not qualified or capable of explaining fuse construction etc, the best thing to do is read the information Bussmann, Littlefuse etc provide.

Fuse or breaker selection can be an important detail to protecting machinery and people.

 

[afoley]

You can go to Bussman, Littlefuse etc and check it out, fuses are designed using the relationship between current, resistance, and heat. If the voltage value increases then the relationship has changed.

Why then, does Bussmann's "fuse Selection guide" available here, list the same KTK-R fuse as applicable for comparative amperage at 120V (AC or DC) and 240V (AC or DC). (And that particular KTK-R is rated at 600V)

 

[hd_coop]

hd I feel like I am being the Devil's Advocate or something, I dont want to be that.

In the construction of fuses they use a relationship between a specific voltage range, current and heat. If you use a 600vdc fuse on a 12vdc ckt do you think the relationship is maintained? In general it may work but it will never work properly.

I am not qualified or capable of explaining fuse construction etc, the best thing to do is read the information Bussmann, Littlefuse etc provide.

Fuse or breaker selection can be an important detail to protecting machinery and people.

Ron you shouldn't feel like devil's advocate. Maybe I should though?
I've been trying to read Bussman's catalog online but I can't seem to get their full-catalog to work which I believe has some info in the back about fuses but I am wondering why they don't list minimum voltages for the fuse? I would think that if the fuse had to be operated within a certain range that they would list the range.

When I first started @ my co-op (3.5 years ago so my memory is a little fuzzy), I took a class at a local vendor about "Fusing Basics" and I don't recall any mention of a minimum voltage. From what I remember the maximum voltage is due largely to arcing, if the voltage applied to the fuse after it blew was too high, it would be capable of arcing across the gap which would defeat the purpose of the fuse.

Sorry for the hijack btw.

 

[Leadfoot]

From what I remember the maximum voltage is due largely to arcing, if the voltage applied to the fuse after it blew was too high,

it would be capable of arcing across the gap which would defeat the purpose of the fuse.

Sorry for the hijack btw.

I am by no means a fuse specialist. Here is some of what I have to deal with routinely.

You can use a 600 volt fuse in a 480v, 250v or 120v circuit of the same amperage and it will protect at the rated amps.

If you were to use a 250v fuse in a 480 volt circuit, the fuse will clear at the rated amperage.

HOWEVER, the fuse and holder tend to explode. I have seen many 230 volt fuses in 480 volt panels and the customer cannot understand why they vaporize. There is that arcing or necessary AIR GAP for stopping arcing. The higher the voltage the better the arc suppression must be when the element clears.

Cut open a couple of fuses and you will see the lower voltage ones are hollow and the higher voltage ones have sand or some other material to help prevent the arcing continuing when the fuse link clears.