dump load on flexmax CC SSR

akamuzz · April 2014

Hi,

Outback FP1 VFX3048E ( 230v 3kw inverter, mate2, Flexmax CC 80a )
2.8kw solar
8 x 12v 65ah batteries (total 130ah @ 48v)

I wonder if you can help.

My setup is at my batch.

It reaches float by 10am. Since I am not home for long periods of time I wish to dump into a water cylinder.

I have a 48vdc 1000w water heater element.

I have purchased some cheap DC SSR's on ebay with no luck they all burnt out and stayed on (NOT Good).

I've also tryed to set up a normal relay 200a, this still burnt as it was continually on, the electromagnet basically becoming a heater.

I have researched DC elements as dump loads, it suggest a diode in the circuit as well.

Can you please recommend a good/decent ssr and type of diode is required for this thanks.

Marty

BB. · April 2014

Re: dump load on flexmax CC SSR

Welcome to the forum Marty.

I deleted your other post--You can use this as your own thread for the discussion--It will make it easier for us to keep the conversation on track.

I guess you are somewhere out of the South Pacific (possibly New Zealand area?). So--Finding parts that work close to you will be more helpful.

Can you tell us what Digital/Mechanical relays you have used so far (URL, mfg name + part number, etc.)?

Generally relays will not overheat if you have the correct coil voltage--They typically only take 6 watts or so (+/-)--Unless you are driving a 12 volt coil from 48 volts or something similar.

Silicon DC Relays have worked for others here (hopefully somebody can give you Mfg P/N)--But one suggest is to make sure you mount the Silicon Relay on a large piece of metal as a heat sink. DC solid state relays tend to get quiet hot at high currents and need good thermal management to keep them from overheating.

I am not sure if you need any diodes in this system... There are snubber/flyback diodes (or capacitors) that are used for DC circuits driving inductive loads (like DC Motors). When a contactor "opens", the inductance of the motor can create several hundred volts of "reverse bias" across the contacts or silicon switch.

http://en.wikipedia.org/wiki/Flyback_diode

-Bill

petertearai · April 2014

Re: dump load on flexmax CC SSR

The other problem you may have is getting a thermostat to switch the dc current. You may need to construct a control circuit as well.
Are you off grid? if so you may find the amount of power available at times is not enough to keep the water at a high enough safe temperature .

zoneblue · April 2014

Re: dump load on flexmax CC SSR

Your problem is that almost all of the ebay SSRs are fakes. The clue there is outrageous specs like 200VDC 100A etc. I took one apart and all there was inside was a single IGBT, and masses of gunk.

You need a quality brand like OMROM or CRYDOM. If you are spending under USD40 then its a fake. Also look up the manufacturers spec sheet, if you cant find one that matchs the part number, then again itll be a fake.

Theres one thing i learned real quick is that there are no shortcuts when it comes to electrical safety.

BB. · April 2014

Re: dump load on flexmax CC SSR

Here are some EBay comments on the knockoffs:

http://www.homebrewtalk.com/f170/reputable-source-ssrs-432418/index2.html

http://www.ebay.com/itm/261125660922

This Fotek SSR was bought on ebay from a counterfeiter in china along with several others, every one has been a knock off to this date. as you can see from the pictures
there is no way it could be a 40 amp relay with what is inside. the heat spreader is thin and the actual "ssr" in side is way to small.

This one fried in 10 minutes under 2/3rds load even with a massive heat sink and fan on it.
and there was no control of amperage going through it with a 500k pot on it.
If your looking for an ssr, don't waste your time with these ones.
This listing is posted to save others from wasting money on P.O.S.'s
When I confronted the seller for this item with emails I didn't get a response.
I have bought from several different sellers in china and have yet to find a real fotek ssr
notice the generous application of hot glue inside to give it some weight!
If anyone has an issue with this listing or complains it's probably because they are
selling fakes.
To make this a "legal" auction I'm "selling" information, the info contained in this auction
and recommendation on which ssr's would be better if your looking to buy cheaper ones than
american made. you can look at my feedback and see who I purchased from recently, this is in no
way endorsement to the other seller but I've bought from them a few times and did full rating
stress test with no failures yet. good luck with what ever your building and happy hunting(parts hunting that is).
update: I noticed that my feedback does not show the last set I bought, which was from this last week
since no feedback has been left yet. I buy the Kyotto SSR's from Taiwan. The ones that I have gotten
have all held up to a full hr. at max rating with only a heat sink on them. The test specs are as follows:

2 - 5500watt 240v water heater elements
amperage and voltage meter with current transformer and clamp meter for measuring.
1 Kyotto 40amp resistants controlled SSR with a 500k pot. and 1 lb. heatsink.
test time: 1hr 15minutes - 10 minutes at 1/2load, 1hr at max 40amps as measured from both meters, then 5 minutes of varying from 1-40amps testing it's ability to control the current

after 1hr. burn in. and yes two 5500watt elements are capable of drawing 45amps, I wanted to have the ability of testing them at max +, the ammeter w/current transformer has a 5:1 ratio
and has a range of 0-50amps, clamp meter is a fluke with 0-1000, set to 200 range while testing. 40amps is set on the lowest reading between the two(fluke meter) and the other is within
a couple tenths.

-Bill

Dave Angelini · April 2014

Re: dump load on flexmax CC SSR

If you do not have any luck getting this to work another route is run a mini split heat pump to heat and cool air or water. LG has 1 ton models that have 28 SEER for heating/cooling air. There are water heaters that work well on heat pumps. Using excess energy is always desirable as long as you are not coming home to discharged batteries or worse. Good Luck

akamuzz wrote: »

Hi,
Outback FP1 VFX3048E ( 230v 3kw inverter, mate2, Flexmax CC 80a )

2.8kw solar

8 x 12v 65ah batteries (total 130ah @ 48v)

I wonder if you can help.

My setup is at my batch.

It reaches float by 10am. Since I am not home for long periods of time I wish to dump into a water cylinder.

I have a 48vdc 1000w water heater element.

I have purchased some cheap DC SSR's on ebay with no luck they all burnt out and stayed on (NOT Good).

I've also tryed to set up a normal relay 200a, this still burnt as it was continually on, the electromagnet basically becoming a heater.

I have researched DC elements as dump loads, it suggest a diode in the circuit as well.

Can you please recommend a good/decent ssr and type of diode is required for this thanks.

Marty

akamuzz · August 2014

Dump before the CC

Thanks all for the replys, another question. should i possibly divert to dump load before the CC?

BB. · August 2014

Re: Dump before the CC

akamuzz wrote: »

Thanks all for the replys, another question. should i possibly divert to dump load before the CC?

I am not sure I understand your question. Are you asking if you should put the Dump Load on the Solar Array Bus before the MPPT Charge Controller?

Normally, you would just put Dump Controller on the Battery Bus--And draw energy to bring the battery voltage back down to 13.0 volts or so... Then the controller turns off and the battery voltage rises aboing to 14.5 volts or so, and the dump controller turns on again.

You can pull the battery bus below ~12.7 volts, but that then starts cycling the battery (discharge by load, recharge by solar).

If the dump load is less than the output of the solar panel--You would just want to turn on the dump load when the battery is full and leave it on until the sun starts going down and the battery bus voltage gets below ~13.x volts (dump exceeds array output)--Then turn off.

I believe that the Outback controllers have a "in float" programmed output you could use as the signal.

-Bill

vtmaps · August 2014

Re: dump load on flexmax CC SSR

BB. wrote: »

When a contactor "opens", the inductance of the motor can create several hundred volts of "reverse bias" across the contacts or silicon switch.
http://en.wikipedia.org/wiki/Flyback_diode

When the magnetic field on the coil collapses the induced current is in the same direction as the current that established the field. Therefore, I don't think the bias on the switch is reversed.

However, there is a reversal of bias on the coil itself. The snubber diode in parallel with the coil only conducts while the coil bias is reversed.

--vtMaps

akamuzz · September 2014

Re: dump load on flexmax CC SSR

Thanks,

Going to go with a Power IO or Crydom SSR, (http://www.power-io.com/products/hdd.htm or http://octopart.com/d1d100-crydom-10251566)

What would the general consensus be on those two above?

Power IO have a Diode available on their website, but what would I use with the Crydom?

The dump load is a 48Vdc 2000w element. With the SSR control running through the AC thermostat.

akamuzz · September 2014

Re: dump load on flexmax CC SSR

Plus looking at a MWANDS Turbine thoughts?
http://store.mwands.com/wind-turbines/2000-watt-missouri-falcon-mach-5-freedom-ii-wind-turbine/

BB. · September 2014

Re: dump load on flexmax CC SSR

I am not a fan of small wind... And in general, PMA alternators (based on automotive alternator designs) are usually not going to give you a good match to a typical wind turbine design.

Looking at their power vs wind speed chart:

http://www.mwands.com/images/turbine/freewind_ii_PC.JPG

What is your average wind speed on a 20 meter (~66 foot) tower?

This chart is in MPH, for 15 MPH or 24 kph or 6.7 meters per second... On their 2kWatt PMA, they will output somewhere around 300 to 400 Watts... How many hours per day (or per month) do you get winds that are 24 kph or higher? You need a good sized tower to put the turbine into clean wind.

Also, if you are Egypt, your only "decent winds" appear to be on the coast of the gulf of Suez... If you are around Cairo/Delta, the area is not known for high(er) average winds and would not be a good site for a Wind Turbine (less than 4 m/s estimated at 50 meters???).

http://www.windatlas.dk/egypt/About.html

If you are still interested in wind--Only spend money that you can "spare" for experimentation. Wind can get expensive (turbines are not that expensive, but towers+foundations, wiring, controllers, battery bank, AC inverter, etc. are generally the majority of costs for wind).

-Bill

akamuzz · September 2014

Re: dump load on flexmax CC SSR

Thanks in Egypt ATM for work, but live in NZ.

Mostly the wind I think the wind will be a toy/trickle charger.
Tower will be 12m high, or 8m if 12 looks to high.

gww1 · September 2014

Re: dump load on flexmax CC SSR

I bought on ebay a crydom 35 amp and can't remember the voltage. I use it from the fm80 charge controller to a 2000 watt 240 volt hot water heater through the inverter. I paid $ 12 something for it. I put it on a great big aluminum heat sink salvaged from a tv I think. I read afterward that 35 amps may be a bit small for the 8 amps the water heater pulls but have had no issues with it over the last year. If I had any issue, it may be that I am not sure that the water heater switches to the bottom element after hitting temp on the top. After four hours or so the ssr light will still be on but the heater won't be drawing power. Then again I don't know how long it takes to heat 50 gal. It mostly does what I need so I haven't checked further. It may break tommorrow but so far so good.

You may wan't to go higher with your tower and not shorter if you do wind. If it is like my wind and you have a charge controller dedicated to it you may even lose charge due to the charge controllers tare loss. I read some where that for every 30 foot up you gain about 10% and it only starts counting for the first 30 above everything within 500 feet.
Wish you well
gww

PS I have an eighty foot tower that only puts me 26 feet above the nearest tree. wind is hard to do, but kind of fun if it is just a hobby.

akamuzz · September 2014

Re: dump load on flexmax CC SSR

gww1
What type of dump load are you using?

gww1 · September 2014

Re: dump load on flexmax CC SSR

It is really more of an opertunity load altough as I have no dumpload for my turbin it helps keep them under load the few times we really get long lasting high winds. It is just a 50 gal hot water heater to pre heat water before it goes into the propane hot water heater. I changed out the 4500 watt elements and put 2000watt ones in it.

The charge controller auxillery activates the ssr to turn it on. I have it set to start turning on at 3 volt before absorb.

Hope this helps
gww

akamuzz · September 2014

Re: dump load on flexmax CC SSR

Attachment not found.
Only HWC diversion shown here.

Ok here is the plan:

SSR POWER IO, 60vdc 70amps controlled by the flexmax 80 diversion SSR Aux out. This will power the 48vdc 2000w element in the Hot Water Cylinder HWC.

Wind turbine through the Midnite classic 250. With 3 phase SSR controlled by the Classic aux. This will power the 1kw resistors.

My plan is to set up the diversion loads at different voltages so:
1. When there is excess voltage the power will be sent to the HWC, when it is up to 80c the thermostat will disconnect power to the cylinder.
2. If the there is still excess voltage from the turbine the 3 phase SSR will connect the turbine to the 1kw resistors.
3. If there is excess voltage from the solar panels, the flexmax 80 will set the batterys to Float.

This way if the water can be heated by both PV and turbine, and when the temp is up in the water, the turbine won't free spin.

I think I've cracked it.

Thoughts?

gww1 · September 2014

Re: Dump before the CC

I hope others comment here as my system is really (I think much simpler) I use ac voltage through the inverter for hot water. So I have the turbines to the battery. The ssr to the cc. and really nothing else. The weakness or my system is I should have a dumpload for the turbine when my hot water is hot enough to turn off.

Heating with dc may be more efficiant but looking at your drawing does not seem quite as simple. All things go to the battery, Soler and turbines. Only one ssr and one cc would use both solar and turbine power. They won't be seperated as the battery is what is feeding the divertion. Having a second divertion load for safty at a higher voltage as to not interfear with the normal workings would be ok. Your resitors could be used for that but need to handle the full possible output of the turbines. Your drawing may be ok but your understanding of some divertion from solar and some from turbine shows a small misunderstanding. I say this with love not out of meaness.
Chears
gww

BB. · September 2014

Re: Dump before the CC

One thing to remember--A diversion load (whether from DC or AC power source) is a "critical circuit" with a wind turbine system... If something fails (DC switching, AC inverter, etc.) or even your water heater is "hot" and thermostat turns off--Then you lose your dump load and risk the wind turbine overcharging your battery bank (boil dry, possible fire/explosion).

A second diversion controller+load (simple air cooled resistor bank) or turbine shut down (such as short on turbine output) is usually a good idea a backup.

-Bill

gww1 · September 2014

Re: dump load on flexmax CC SSR

Again I hope those smarter then me chime in. I really recomend that you use good heatsinks for your ssrs.
gww

gww1 · September 2014

Re: dump load on flexmax CC SSR

Bill posted while I was typing and I agree with what he says. My typing sometimes put an r when I wanted to type an f so bare with me. He points out the weakness of my system as I tried to do. The air cooled divertion needs to cover the full maximum out put for your turbine or shut it down. I worry about the shut down in high winds to be pretty violent but pretty full proof. Some have used it with success and I do have a manual one. Manual is not optimum as it can be forgotten.
Are you confused yet?
gww

akamuzz · September 2014

Re: dump load on flexmax CC SSR

I Understand.
But this is only the HWC diversion pic, there is another stand alone system for the turbine. In number two.

2. If the there is still excess voltage from the turbine the 3 phase SSR will connect the turbine to the 1kw resistors.

I had a SSR AC element but, the lights in the house would flicker as the AC was switched on and off by the AC SSR...... not good for equipment I guess.

I think its pretty simple in my eyes. With a back up

BB. · September 2014

Re: dump load on flexmax CC SSR

As long as your system is "safe" with a single point failure (i.e., a diversion load/controller failure)--That is all that is needed (you need to ensure that you can recognize a single failure too so that you don't have two failures at the same time--Not always obvious).

Also, the SSRs generally should be mounted on a good sized metal heat sink--they can get very hot (and fail) if not kept cool.

-Bill

gww1 · September 2014

Re: dump load on flexmax CC SSR

akamuzz
My lights also flicker when the ssr is not at full power. I guess I have gotten used to it. I am not sure if it causes damage or not. It flashes a bit when my well pump kicks on also. I called outback and they said it was due to the speed of the inverter. It usually doesn't last to long untill the load is on 100 %. I didn't comment on the samatic being correct or not cause like you I would have had to ask someone else to know.
Cheers
gww

akamuzz · May 2015

Ive gone for a crydom D1D1000 http://www.crydom.com/en/products/catalog/d_1_d.pdf, works very well with 1-3kw DC element. Heats the cylinder up to 80 degrees before the thermostat turns it off. reduces the gas bill on the water heater.

dump load on flexmax CC SSR

Comments

Categories