Would this be a decent relay?

[axro]

I'm going to be building a timer circuit that will power a oscillating floor fan and maybe a cellphone charger at the same time. I was looking for a relay and I found this:

New in Box Solid State Relay SSR 24-480V AC, 25A - eBay (item 250468419696 end time Aug-18-09 17:52:47 PDT)

On paper it sounds awesome. only 25mA to turn it on and it can switch 25A. But are these junk? Going to burn down my house? What is your opinion?

 

[MikeMl]

These work well as switches for resistive loads. Less so for inductive loads like a motor. Also, it is not good to use a 25A SSR to switch a light load less than an A or two.

 

[q5101997]

I know very little about SSR's (nothing actually), but I would be concerned about leaving high voltage stuff turned on while you are away, especially if the circuit is untested.

Regs Q

 

[mramos1]

If you're worried about the brand. mpja.com has surplus SSRs on their website. I have bought and used many over the years with no issues. We have a 12" Christmas wreath that pulls about 25 amps. I broke the load in two runs to two 15 AMP SSRs. Runs every year and for many days with no problem.

 

[tcmtech]

The basic rule with SSR is to not use a SSR that rated at over 10x the average running amps to 5x the applied voltage. So for a 25 amp rated SSR using less than 2.5 amps can cause some of the cheaper brands to have switching problems. Some times they dont come on and stay on properly.
The good brand units now have very low minimum current ratings.
I have some with 100 amp ratings with a 50 MA minimum rating. But they also have an 80 - 400 volt rating and wont work properly under 80 volts.

Why would you want to be continually switching between a fan and a cell charger?

 

[axro]

The basic rule with SSR is to not use a SSR that rated at over 10x the average running amps to 5x the applied voltage. So for a 25 amp rated SSR using less than 2.5 amps can cause some of the cheaper brands to have switching problems. Some times they dont come on and stay on properly.
The good brand units now have very low minimum current ratings.
I have some with 100 amp ratings with a 50 MA minimum rating. But they also have an 80 - 400 volt rating and wont work properly under 80 volts.

Why would you want to be continually switching between a fan and a cell charger?

Oh, thats not what I'm doing. I'm going to have the relay power an outlet that runs for about 2hours and then shuts off. I just thought it would be a fun project to do.

The reason I said a fan and a cell charger is that I don't need a fan all night, and it would shut off afte the given time, and with the cell charger, I could plug it in before I go to sleep and have it charge but not be plugged in all night.

 

[tcmtech]

Dont cell chargers have automatic standby modes when charging any more? Or is there so much useless junk packed into cell phones now that they couldn't fit that into them any more?

 

[BrownOut]

Dont cell chargers have automatic standby modes when charging any more? Or is there so much useless junk packed into cell phones now that they couldn't fit that into them any more?

Even if they do, they, like many other appliances, continue to draw power just be being left plugged in. By theirselves, it's not much, but as I, for example, have many of these types of appliances, plugged in constantly, they can add up to a pretty significant amount of wasted power. It's not so much that I can't afford to pay my utilities bills, but it's just waste, which is never good. Having an automatic shut off for some of these things is an excellent idea, in my opinion.

 

[tcmtech]

So how many hours do they have to be shut off in order to justify the avoided cost savings that would equal what a the SSR and timer system would cost to make?
A few tens of thousands of hours maybe?
Or about 200 years of oops I left it plugged in over night again's!

Since your on a quest to save power I am going to leave some stuff plugged in over night to off set your savings!

 

[BrownOut]

Tens of thousands of hours to recoup $10 worth of parts? Esitmates of passive power usage have show that it can cost consumers about $80 US per year to leave all the miscellaneous wall warts plugged and energized. And that's with energy cost at it's present low cost. Don't be fooled into thinking the cost to always stay this low. The cost of wasting energy is much more than just the check you have to write to your utility company. Fortunately for me, I was raised to not waste any resources even before we knew how much damage it can potentially do to our environment and society.

 

[tcmtech]

I checked out my charger for my cell phone. It says 7 watts max. So I assume 3 watts standby would be realistic being its a switcher type and not transformer type. So given I pay about 12 cents a KWh

1000/3 = 333.3 Hours per Kw consumed.
$10/.12 = 83.3 KWh for $10
83.3 x 333.3 = 27775 hours for my ten dollars.

So for me a few tens of thousands of hours seem pretty realistic.
And factoring in there are 8765 hours in a year.
That would mean I could leave it plugged in for about 3.16 years.
Or leave it accidentally plugged in on occasion for around 200 years of twice a week oops I forgots!

You may seriously want to look at your clock radios though. all of mine are rated at 12 -15 watts! And the run 24/7/365!

I am not trying to be a jerk but I do tend to play the devils accountant whenever I can with the environmentalists!
I have yet to find any numbers the enviro nuts toss around to be even remotely true let alone even loosely based on real facts. I find someone else's ignorance, foolishness or misguided logic to be no reason for me to change my ways. Prove the reasons scientifically and accurately with repeatable and provable evidence and I will happily change my ways!

I believe that being environmentally conscientious is a good thing but I prefer to go after the bigger issues. Cell phone charger efficiency is nothing compared to what your home heating and cooling systems use or your essential convenience items in general.
And I have reduced my home power usage by nearly half in one year by dumping some inefficient big power use items!

 

[crutschow]

Of course the timer circuit will also require power. It will only save energy if the units you are controlling uses significantly more energy over a day than the timer circuit (which I assume would be powered from another wall-wort). A cell phone charger may not. I believe the new ones use less than a watt when not charging (and perhaps also when the phone is fully charged). If the charger feels cool when it's not charging then it's using very little power.

 

[Boncuk]

An "Anti-Standby-Switch" certainly makes sense with my home theater using 90W in standby mode.

 

[BrownOut]

I checked out my charger for my cell phone. It says 7 watts max. So I assume 3 watts standby would be realistic being its a switcher type and not transformer type. So given I pay about 12 cents a KWh

1000/3 = 333.3 Hours per Kw consumed.
$10/.12 = 83.3 KWh for $10
83.3 x 333.3 = 27775 hours for my ten dollars.

So for me a few tens of thousands of hours seem pretty realistic.
And factoring in there are 8765 hours in a year.
That would mean I could leave it plugged in for about 3.16 years.
Or leave it accidentally plugged in on occasion for around 200 years of twice a week oops I forgots!

You may seriously want to look at your clock radios though. all of mine are rated at 12 -15 watts! And the run 24/7/365!

I am not trying to be a jerk but I do tend to play the devils accountant whenever I can with the environmentalists!
I have yet to find any numbers the enviro nuts toss around to be even remotely true let alone even loosely based on real facts. I find someone else's ignorance, foolishness or misguided logic to be no reason for me to change my ways. Prove the reasons scientifically and accurately with repeatable and provable evidence and I will happily change my ways!

I believe that being environmentally conscientious is a good thing but I prefer to go after the bigger issues. Cell phone charger efficiency is nothing compared to what your home heating and cooling systems use or your essential convenience items in general.
And I have reduced my home power usage by nearly half in one year by dumping some inefficient big power use items!

I believe there was a mention of a fan to be switched too. I have two industrial duty fans that blow air through my relatively cool basement and into my house for passive cooling. They draw about 100W each. Those two fans alone cost about 115 bucks per year, running them for about 8 months in Alabama. Aside from a phone charger, there are TV's stereos, DVD players, computers, routers, switches, etc. The more of these appliances you can switch off at night, the less energy ( money ) you are wasting. Since you're such a math wiz, consider this: he might only save his original $10 investment the first year by cycling his fan and phone charger. Then, maybe he adds a second outlet in which he pluggs in TV's, stereos, etc. Now, he has the potential of saving up to $80 per year. Now, he's getting 8 times his investment back every year. If he builds and sells his invention, then each house hold who has one installed saves the same $80 on average. If 50 million homes have one of these, we're talking about potential savings of near 10's of billions of kilowatts. Not small potatos. Saving energy creates more economic opportunity, makes the environment cleaner, saves more of the polar ice caps.


Or think of it this way; what did we pay for out last attempt to seize mid east oil??? Estimates run as high as 2 trillion dollars. That's nearly $7,000 for every man, woman and child in the US. A killowatt of electricity costs us much more than that little number printed on our bill.

 

[audioguru]

The cheap Chinese junk is not approved to be used in North America nor in Europe.
It might burn down your home and the insurance company will see that it is not approved and say, "Too bad".

Why do people buy cheap chinese junk? Because it is cheeeeep?

 

[tcmtech]

Awfully big what if you bit off there!
Sure you can chew it properly?

 

[BrownOut]

Isn't that what Xerox said about the PC?

 

[BrownOut]

The cheap Chinese junk is not approved to be used in North America nor in Europe.
It might burn down your home and the insurance company will see that it is not approved and say, "Too bad".

Why do people buy cheap chinese junk? Because it is cheeeeep?

Does that mean we can't use any of the electronics sold at Wallmart in our homes?

 

[audioguru]

Many local stores (like Wal-Mart) and manufacturers have their products made in China but they make sure they are made safely and have the approvals done properly.

My electrical utility gave away compact fluorescent light bulbs. Guess where they were made? Some caught on fire then they discovered that the approval number was a counterfeit! They were all replaced.

 

[axro]

This thread is getting a little out of hand haha.

First of all, it's not entirely about saving electricity. While yes, I do want to save more electricity, it's also a fun little project to make. One that will actually do something useful instead of just flashing some LED's.

So for my needs, what you are saying is I should use a Mechanical Relay instead of an SSR? I don't know how much current my fan uses. I took a quick look on the fan and didn't see any labels. I will have to do a little more searching to see if I can get some numbers.