Conext SW and AC Pass Thru Loads

MrM1MrM1 Registered Users Posts: 473 ✭✭✭
Wondering how much load the SW can Pass thru when in AC Pass thru mode and NOT in Inverter OR AC Support mode.   I am sure it is limited to the in  and out breaker and wire size connected to it,  but is there a limit beyond that?   In other words,  can the SW actually pass thru any amount of Current / Power,  say 4000 or 6000 watts - at least for a few minutes.  Maybe even more.  Just wondering what the limits of the unit are and what if any effect passing thru high loads might be.

Thanks
Mike
REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2017 / System, Pics and Discussion

Comments

  • mcgivormcgivor Solar Expert Posts: 3,119 ✭✭✭✭✭
    Since the AC input has to qualify before transfer to within certain parameters, voltage, frequency etcetera, it would make sense the SW would actually rectify then invert the input before sending it to the loads. If this is the case, the amount pass through  current allowable would be  the same as the rating of the unit, up to a maximum of 25°C, derating above that.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery bank 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah FLA 24V nominal used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
  • MrM1MrM1 Registered Users Posts: 473 ✭✭✭
    Trying to wrap my head around what you are saying (pardon my ignorance).    Are you saying it is always inverting even when merely passing thru from grid to loads?   I can turn the inverter and charger off in the SW (but not switch off the SW itself) in the Combox.  If connected to an AC source such as the grid or a generator,  the combox is still reporting that power is passing thru the SW.   Is inverting taking place anyway? 
    Or are you simply saying that the SW is rated for what it is rated for and can (or at least only should) out put what it is rated to output regardless of how it is "getting" that power:  inverted from the battery, passed thru from the grid or generator. 
    REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2017 / System, Pics and Discussion
  • mike95490mike95490 Solar Expert Posts: 8,429 ✭✭✭✭✭
    edited January 24 #4
    Pass Thru limits are set by the internal relay contacts.  If I recall correctly, my XW6048 has 60A 240VAC rating on the AC relays.  They might take a bit more, but I hear welded relay contacts are common in inverters, I never push mine to the limits.

    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • mcgivormcgivor Solar Expert Posts: 3,119 ✭✭✭✭✭
    edited January 24 #5
    MrM1 said:
    Trying to wrap my head around what you are saying (pardon my ignorance).    Are you saying it is always inverting even when merely passing thru from grid to loads?   I can turn the inverter and charger off in the SW (but not switch off the SW itself) in the Combox.  If connected to an AC source such as the grid or a generator,  the combox is still reporting that power is passing thru the SW.   Is inverting taking place anyway? 
    Or are you simply saying that the SW is rated for what it is rated for and can (or at least only should) out put what it is rated to output regardless of how it is "getting" that power:  inverted from the battery, passed thru from the grid or generator. 


    Actually the reply is a question of sorts, reading the manual it states the AC in first has to qualify, once accepted bypass current will be passed to loads. Once the qualifications fall outside the programed parameters, AC will be disconnected and inverter will resume the load support. The specifications for the SW states, Maximum continuous allowable  (in pass thru) 30A, for models 2524, 4024 and 4048, so this would indicate it is not rectified then inverted. The question is, since the inverter peak output for the SW models listed are, 11,16 and 16A respectively, should the pass-thru ever exceed that value, a value the inverter cannot support on a continuous basis, the inverter would fault on overload.if the AC disconnected. Please understand I'm just trying to rationalize how this would function as the manual really has no theroy of operation.  Currently i only use AC for charging if required, but hopefully that will change when grid becomes available, currently I'm 450 meters from the nearest pole, 1300 meters to transformer where the higher voltage lines are.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery bank 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah FLA 24V nominal used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
  • MrM1MrM1 Registered Users Posts: 473 ✭✭✭
    Thanks, Mike and Mcgivor.  Yes welded contacts would equal bad.  Not that i was planning on exceeding the limits of the inverter,  but was more concerned about momentary or very short loads, say in the 5 second to 3-5 minute range that might get up to 4000W for the longer duration's and 5000W+ for start up surges.  Sounds like just stay within the inverter limits for both pass thru and inverting.   Specs for the SW 4024 are 3400W continuous,  4000W for 30 minutes, and  7000W for 5 seconds at 25°C.   The 48v version is slightly higher in the first 2 but the same for 5 seconds.
    I continue to tinker with getting my loads more and more balanced both in "normal" use and those larger short loads like vacuums, hairdryers  and small microwave. The Autotransformer has helped to "insure" I am not overloading one side of the 240v SW,  but if everything came on at once, things might get near the limits.  Did not know if the inverter would invert what it could and then pass thru the rest or just shut down if limits were exceeded. 

    REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2017 / System, Pics and Discussion
  • mcgivormcgivor Solar Expert Posts: 3,119 ✭✭✭✭✭
    Welding of contacts will be a problem if a transfer is made or broken under load, when an arc is most likely to occur, once made, the surge rating is probably much higher, age will also degrade the contact surface making them more prone to failure.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery bank 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah FLA 24V nominal used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
  • EstragonEstragon Registered Users Posts: 4,101 ✭✭✭✭✭
    Even setting aside the contact arc issue (assuming the pass-though relay is made  and stays closed), I'd avoid going much over the pass-through current spec for anything other than a momentary (eg motor start) load.  The internal wiring is presumably sized to meet the pass-through current spec, and running say 2-3x the spec current for several minutes seems unwise.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • BB.BB. Super Moderators, Administrators Posts: 29,637 admin
    Not an answer directly, but a warning... Relay contacts tend not to have a lot of thermal mass (they are generally lightweight so that they can turn on/off quickly).

    And remember that one equation for power is Power=Current^2 * Voltage... So that if you double the current, you get 4x the heating (Watts).

    I would suggest that you avoid dramatically large over current situations.

    However, for example, 2x surge surge power support is a typical rating for a good quality AC inverter (few seconds to a few minutes). And surge current of 5x rated load is common for induction motor starting and even some (older) larger (my experience was with older computer power supplies) electronic power supplies (for a couple of 60 Hz cycles).

    As long as you are staying within the above surge current/power/VA range, it would seem to be allowed.

    But, as always, thermal cycling and high temperatures are the enemy of electronics (almost anything physical).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490mike95490 Solar Expert Posts: 8,429 ✭✭✭✭✭
    Your data sheet for your inverter should state the surge specs the inverter can support.   My XW:


    At 11 sec, it starts to fall off.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • MrM1MrM1 Registered Users Posts: 473 ✭✭✭
    edited January 25 #11
    right Mike ... it does,  and from what you folks are saying, the surge rating for inverting would also be the surge rating for pass thru.  That is what was wondering.   Could the SW pass thru more than it was rated for in inverting OR supply more than it was rated for from 2 sources - grid/generator and battery?   Sounds like probably not.


     I was kicking this all around in the context of AC Support Mode which has never preformed up to spec in the SW's.   So since knowing the SW will NEVER supply more than about 70% for large loads (except in the cases of perfectly balanced loads like 240v pumps etc),  was wondering if it would be OK to have say a 5000 watt load,  that the inverter was supplying about 3400 watts of (the max of the inverter) and the pass thru grid was supplying the other 1600 watts.   But it sounds like a bad idea.


    REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2017 / System, Pics and Discussion
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