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DC SSR size?

Started by kauaisolarman, January 21, 2017, 12:17:56 AM

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dgd

Can you get a meter and measure the actual resistance of that MWANDS heating element?
Dgd
Classic 250, 150,  20 140w, 6 250w PVs, 2Kw turbine, MN ac Clipper, Epanel/MNdc, Trace SW3024E (1997), Century 1050Ah 24V FLA (1999). Arduino power monitoring and web server.  Off grid since 4/2000
West Auckland, New Zealand

mike90045

Quote from: kauaisolarman on January 21, 2017, 08:52:38 PM
....checked continuity with my gauge today and when i put the gauge to the beep/sound setting i get a beep when testing between my main + busbar and the negative (-) terminal on the AUX 2...... 

Was the gear powered OFF everywhere when you did cont test ?  Any stray voltage can disrupt the beep test.
And when you do cont testing, test it once, then swap the test leads around and test again, sometimes, polarized electronics (transistors, diodes, caps charging up from the meter power) can fool the test gear.
http://tinyurl.com/LMR-Solar

Classic 200| 2Kw PV, 160Voc | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph )| Listeroid 6/1, st5 gen head | XW6048 inverter/chgr | midnight ePanel & 4 SPDs | 48V, 800A NiFe battery bank | MS-TS-MPPT60 w/3Kw PV

mike90045

snubbing diodes.   Beyond my skills to describe over the internet, how to install them, perhaps the SSR factory data sheets have simple outline suggestinons.   

As to PWM switching, DC SSR's have limited frequency response to PCM signals.  beyond a couple Hertz, I don't trust them.

Breakers -  Depending on the style (thermal or magnetic) you get a very broad response (thermal) or precise response (magnetic)   Breaker needs to be able to trip, don't oversize it too much, it has to carry the heater load 100%.  Size the wire to be safe 1 gauge beyond the breaker trip point.  55A breaker, use 70A rated wire.  Your desired amps will be at the high end of the float voltage.

AC load vs DC load.   Add an inverter to the mix and use the inverter to drive the heater ?   Maybe a signal relay can control the inverter remote On / Off ?   Can the inverter start up under a stiff load ?
http://tinyurl.com/LMR-Solar

Classic 200| 2Kw PV, 160Voc | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph )| Listeroid 6/1, st5 gen head | XW6048 inverter/chgr | midnight ePanel & 4 SPDs | 48V, 800A NiFe battery bank | MS-TS-MPPT60 w/3Kw PV

kauaisolarman

thanks

aux 2 waste not Hi being used for PWM to the switch side of the relay.

i didn't get to call solidstarerelaystore but i will on Monday.  hopefully they can point me in the right direction and get my DC diversion load setup.

I was reading somewhere that if running more than 30A through a SSR it needs forced airflow over the heatsink to prevent overheating.  can anyone confirm this.

as stated earlier i am running about 47Amps through the relay so maybe thats whats causing them to busn up within 1-2 mins.

seems like with that much heat to deal with over the long run DC water heating off the battery might not be the best way to approach this.  with AC there are much lower amperage passing through the relay and way less heat prolong life of the components.

any thoughts
2 solar systems in progress;
1. 24V interstate battery; 5x sanyo hit 190Watt in parallel to classic 150-SL + 8x Shell 140 watt series/parallel to classic 150-Sl (follow me).

2. 48V aquion battery; 6x panasonic HIT 325, 6x suniva 315,  CC TBD.

mike90045

regarding heat.  Forced Air  - Baloney.   The FETs in a 60a charge controller don't have forced air.  A good DC SSR @ 0.4V drop, 50A, is only 20 watts.   There are many 20w passive heatsinks.  Desktop Computer CPU's are 100w roughly. big heatsink, quiet fan.
Or maybe a DC contactor from a golf cart is the way to go.
http://tinyurl.com/LMR-Solar

Classic 200| 2Kw PV, 160Voc | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph )| Listeroid 6/1, st5 gen head | XW6048 inverter/chgr | midnight ePanel & 4 SPDs | 48V, 800A NiFe battery bank | MS-TS-MPPT60 w/3Kw PV

TomW

Quote from: mike90045 on January 22, 2017, 11:01:11 PM

Or maybe a DC contactor from a golf cart is the way to go.

Fine on a on / off output. 

Not on a PWM output like he is using, for clarity to those that may not know it.

Quoteaux 2 waste not Hi being used for PWM to the switch side of the relay.[/unquote]

Exactly why forum advice needs to be carefully considered.

Just saying.

Tom
Do NOT mistake me for any kind of "expert".

( ͡° ͜ʖ ͡°)


24 Trina 310 watt modules, SMA SunnyBoy 7.7 KW Grid Tie inverter.

I thought that they were angels, but much to my surprise, We climbed aboard their starship and headed for the skies

TomW

#21
Quote from: TomW on January 23, 2017, 11:39:20 AM
Quote from: mike90045 on January 22, 2017, 11:01:11 PM

Or maybe a DC contactor from a golf cart is the way to go.

Fine on a on / off output. 

Not on a PWM output like he is using, for clarity to those that may not know it.

Quoteaux 2 waste not Hi being used for PWM to the switch side of the relay.

Exactly why forum advice needs to be carefully considered.

Just saying.

Tom
Do NOT mistake me for any kind of "expert".

( ͡° ͜ʖ ͡°)


24 Trina 310 watt modules, SMA SunnyBoy 7.7 KW Grid Tie inverter.

I thought that they were angels, but much to my surprise, We climbed aboard their starship and headed for the skies

kauaisolarman

#22
thanks again everyone for the replies.

so the struggle continues.   the heating element i am using is basically 2 1000W elements on 1 screw in rod that is paralleled together to get the 2K watts.

i have disconnected the parallel connection and now an only pulling 1000watts off the heating element.

same results as before, but, this time it will work for a little while longer before remaining in the shorted out "on" position.

measured the amps going through the emenent configured at 1K watts and i get 25Amps max.   

I am using a 100Amp heatsink and it gets to 145 degrees F.

with only 25 amps going through the DC SSR it lasts a little longer than the 47A but still burns up eventually.

when i did my initial tests yesterday at 25A i could leave the relay on for up to 5 mins (thats when it got to 145F) and it would still turn off usning the aux 2 manual controls so i though that my problem was solved, but, today i had it set on "waste not HI"  and it worked great for the first 15 mins of the absorb cycle (switching on and off properly keeping me at absorb) but then when i went back to check on it about 20 mins later it was stuck in the "on" position again.

going to call solidstaterelaystore and see if they can help.

any other suggestions?

anyone running a DC SSR with high amperage like me?  how/what did you do to get your setup running properly.

thanks again everyone.

2 solar systems in progress;
1. 24V interstate battery; 5x sanyo hit 190Watt in parallel to classic 150-SL + 8x Shell 140 watt series/parallel to classic 150-Sl (follow me).

2. 48V aquion battery; 6x panasonic HIT 325, 6x suniva 315,  CC TBD.

CDN-VT

Use two 40 AMP bosch relays that are 12 Vdc contact , They can handle 80A in Parl-mode .Or Much larger ones that can handle huge amps with a small pull in / keep power.

VT
Canadian Solar 350W 37.6 VOC  30.6 VMP 8.22 ISC 7.87 IMP ,-15 c +30c max  4 strings in 2 in Series for 24v Classic 150 -1020 Ah  Freezers & fridges ~~~ Second Array same panels of 3sx3 parallel for 24 V Classic 150 -440 Ah Outback Barns & out blds.
48Vdc almost done,11Strings up of 3s11P same panels

kauaisolarman

Ok so heres an update.

possible aux 2 12V (actually 15V for me) signal messing with load going to heating element.

so the other day with everything installed i used the aux 2 manual on/off to test if the SSR would actually turn on and off without burning up and staying in the on position.   it did work, but, the relay and heat sink say temps of 145F!  all this while running 24-25 Amps @ 50-54V to the heating element (1000-1400 watts roughly)

today i set it on waste not hi to see if it would hold up and it was working well for about 20 mins then the ssr got stuck in the "on" position again.   

at this point i turned aux 2 to manual off position and was using my load DC circuit breaker to turn on/off the heating element.

anyway what i observed was that with AUX 2 in manual OFF (wires still connected to SSR) and heating element turned on (24A@53V) there was little to no heat produced by the SSR.   left it on continuously for 20 mins and no heat produced.

before the relay got stuck in the "always on" position it would get extremely hot when using the aux 2 pwm 12V signal to activate the load, but after it got stuck in the shorted "always on" position  with the same amount of power flowing to the heating element the relay was not producing any heat when not being activated by the aux 2 12V signal.

is there any way the aux 2 signal is causing a short in the relay and producing all the heat that i was seeing and toasting my relays?

i though that the signal 3-32V that activated the switch to turn on/off the load was totally separated from the load amperage and voltage inside the SSR?   

seems like my problem is the load is grounding/shorting out through the relay to the 12V source side of the relay.

will do more testing tomorrow and post results.

called SSRstore today but no answer.
2 solar systems in progress;
1. 24V interstate battery; 5x sanyo hit 190Watt in parallel to classic 150-SL + 8x Shell 140 watt series/parallel to classic 150-Sl (follow me).

2. 48V aquion battery; 6x panasonic HIT 325, 6x suniva 315,  CC TBD.

Taos

Can you draw up a schematic of your wiring and post it as it seems like your ssr is wired incorrectly and once energized by the charge controller it completes a short circuit. By drawing the circuit it would be less confusing ,also it would be helpful if you tell us were your are mesuring on the circuit for amps and voltages .precission in electrical makes a big difference (it works or it doesnt work )  doesnt make sense that there were many ssr burned up and different brands of ssr ,when they heat up that fast there either shorted out internal (defective) wired incorrectly,supper cheap relays, wrong relay used for load rating or voltage . Sounds like With all that heat the relay becomes your hot water heating element ( direct short ) like i said #1 we need to see your wiring schematic first to be capable of diagnosing properly.
Don
400watt x12= (4800watts)Canadian solar panels,ground mount, (400 AH ) 16 Ao lithium 12volt 100ah 4s lithium  batteries , outback vfx3648 inverter 48 volt,midnite solar classic 150 charge controler,midnite solar e panel mne175al,3 surge protectors,wiz bang junior.

mike90045

Are you switching the SSR with a PWM signal, or simply On - Off with a few seconds between switching ?

The SSR in full conduction is very low power.  But if it's Switching Off-On-Off at a faster rate than 2Hz, you are operating it in pulsed mode where it can build up a lot of heat.

There are expensive SSR that can be rapidly switched, but you pay a lot extra for them
http://tinyurl.com/LMR-Solar

Classic 200| 2Kw PV, 160Voc | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph )| Listeroid 6/1, st5 gen head | XW6048 inverter/chgr | midnight ePanel & 4 SPDs | 48V, 800A NiFe battery bank | MS-TS-MPPT60 w/3Kw PV

kauaisolarman

Quote from: mike90045 on January 27, 2017, 11:28:22 PM
Are you switching the SSR with a PWM signal, or simply On - Off with a few seconds between switching ?

The SSR in full conduction is very low power.  But if it's Switching Off-On-Off at a faster rate than 2Hz, you are operating it in pulsed mode where it can build up a lot of heat.

There are expensive SSR that can be rapidly switched, but you pay a lot extra for them

i am using the same aux 2 PWM signal to switch another water heater element that works perfect just with AC instead of DC. (on a completely separate system)

i am using DC power on the current system i am talking about but the same type of SSR.

i will draw up a diagram and take some pics tomorrow

contacted SSRstore and got some advise about flyback diodes and some sort of capacitor clost to the SSR to clean up the power signal next to the relays.

will keep posting until everything is sorted out.

thanks for all the input.
2 solar systems in progress;
1. 24V interstate battery; 5x sanyo hit 190Watt in parallel to classic 150-SL + 8x Shell 140 watt series/parallel to classic 150-Sl (follow me).

2. 48V aquion battery; 6x panasonic HIT 325, 6x suniva 315,  CC TBD.

kauaisolarman

Quote from: TomW on January 21, 2017, 02:56:48 PM
Quote from: ClassicCrazy on January 21, 2017, 01:55:15 PM
Maybe you need to move up to something more substantial like a contactor.  For all the relays you have burned up this probably is the same price.
Check with the EV parts place or the Gigavac - I am sure they will give you info on the correct product to do what you want it to .

http://www.evwest.com/catalog/product_info.php?cPath=2_13&products_id=407
http://evwest.com/support/gv200.pdf



Larry

Absolutely, if it is  an on / off application and not PWM driven.

Tom

what if i use the load side of the contactor for PWM (from a separate PWM diversions controller). and the 12V switch side just normal on/off application? (set aux 2 to manual on all the time and running 12V through thermostat then to contactor)

would that work with this type of contactor?

in other words if the contactor is in "on" position (allowing power to flow through) and i send a PWM load through the contactor (max 47Amps@57V) will it handle the PWM load and not need flyback diodes across the contactor load terminals?

just thinking of possible other options if the direct battery to SSR method doesn't pan out.

thanks again
2 solar systems in progress;
1. 24V interstate battery; 5x sanyo hit 190Watt in parallel to classic 150-SL + 8x Shell 140 watt series/parallel to classic 150-Sl (follow me).

2. 48V aquion battery; 6x panasonic HIT 325, 6x suniva 315,  CC TBD.

mike90045

Quotei am using the same aux 2 PWM signal to switch

I think if you contact the SSR Mfg, they will say you CANNOT use pulse mode as a trigger.
You can use DC on and off, but not PWM, that will quickly violate the specs, and they will burn up.
http://tinyurl.com/LMR-Solar

Classic 200| 2Kw PV, 160Voc | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph )| Listeroid 6/1, st5 gen head | XW6048 inverter/chgr | midnight ePanel & 4 SPDs | 48V, 800A NiFe battery bank | MS-TS-MPPT60 w/3Kw PV