EMS question

[fly2low]

I was reading another thread which got me to thinking about my situation. I have a PI EMS-HW50C hardwired into my system after the transfer switch. So far, no problem with that.

Recently I switched to an inverter which can augment the generator or line voltage if my needs exceed their input.

It would seem to me that my inverter may never get the chance to augment either one if the EMS does what it should do.

I suspect I am missing something, but not sure what it is.

 

[SCClockDr]

Knowing the brand and model of your new inverter might prove helpful to us reading. A note as to where it is located in your AC power stream would also be helpful.

[oldjohnt]

flylow, When you say you " ...have a PI EMS-HW50C hardwired into my system after the transfer switch"

 

1) Am I correct in assuming by "after" you mean your EMS is wired to the transfer switches OUTPT (two INPUTS would be Utility OR Genset) in which case it monitors whichever INPUT (Utility OR Genset) source your switch has selected??????????????? That's NOT where I would have located it for certain technical reasons, but that's another topic and not your question, so I'm NOT addressing it for now at least. I assume your transfer switch OUTPUT feeds your RV's AC Distribution Panel with your EMS in series between is that correct???????????

 

2) Next question would be what all equipment do you wish your Inverter to operate when its running????

 

An Inverter is just one more source of available 120 VAC power, similar to your current Utility OR Genset. In the event (which I doubt) you wished to supply all your current RV 120 VAC loads from EITHER Utility orrrrrrrrr Genset orrrrrrrrrrrr Inverter that would require a three in one out transfer NOT any typical method or device. Of course unless an Inverter is extremely high rated and you have a ton of batteries, its not going to supply allllllll your loads, but I'm sure you already know that.

 

When you say you want the Inverter to "augment" the generator, in case you aren't already aware, when two different energy sources (like when a guy uses two smaller generators in parallel) THEY MUST BE FREQUENCY SYNCHRONIZED. IE you cant just (absent frequency synchronization) use two sources in parallel to feed AC power.

 

One method for those who use an Inverter to feed relatively small loads like to charge phones and laptops and run a small TV or electronics, is just to have a few dedicated receptacles into which they can plug such items THATS NOT CONNECTED TO THE REST OF THE RV'S AC DISTRIBUTION. The Inverter simply supplies maybe a dedicated outlet power strip to charge and run small electronic devices or maybe bigger subject to inverter and battery capacity

 

I'm trying my best to help and not confuse but I need to know more before I can render more advise. WHAT DO YOU WANT TO POWER OFF YOUR INVERTER??

 

PS it appears you have a 50 amp RV which makes the whole transfer switch issue a bit more complex. The Inverter could be used to supply a portion of ONE LEG of your distribution panel or separate sub panels etc etc. I have seen Inverters wired to sub panels so ONLY certain dedicated loads are supplied. I just need to know more.

 

PS are you expecting or desire your Inverter to also tied into your EMS ????????????? Its MUCH cheaper and simpler to just feed a few dedicated receptacle or power strips via the Inverter and NOT mess with or tie to the rest of your system.

 

PS the whole issue of Single Point Grounding and proper Neutral Ground BONDING also needs to be considered. It never ends lol

 

John T

[Jack Mayer]

John, there are various inverters on the market that do supplement AC line power with battery power. They monitor the line and sych power on demand, augmenting a load demand that cannot be satisfied with the shore power, with inverted battery power.

 

A typical use in the "RV World" might be plugging into a garage 15 amp outlet while driveway boondocking. In that case power can be shared between what is available from the garage and the battery bank.

[oldjohnt]

Thanks Jack, as we already knew, of course they MUST be synchronized and not sure from reading the post he was aware of that, BUT HE IS NOW. Once we know his needs and what equipment he has (including sync ability) we can help more.

 

As always I enjoy your sparky chat

 

John T

[Kirk W]

First, I assume that you mean a Progressive Industries (PI) EMS of 50a for the RV. Are you sure that it is electrically after the transfer device, as it if far more common to have them on the shore power cord, prior to the transfer device? To be sure I'd need to either see the schematic for the RV or investigate with a good meter.

Recently I switched to an inverter which can augment the generator or line voltage if my needs exceed their input.

It would seem to me that my inverter may never get the chance to augment either one if the EMS does what it should do.

I suspect I am missing something, but not sure what it is.

Again, it would depend upon how the inverter is designed and how connected. If the inverter monitors incoming voltage, then chances are the EMS would open before the inverter took part of the load if the inverter does so based upon monitoring voltage. To know for sure we would need to know what it senses to cause it to do the load sharing thing. I am not very knowledgeable on these devices so don't know what it is monitoring.

[fly2low]

Inverter = Victron Multiplus 12/3000/120

https://www.victronenergy.com/inverters-chargers/multiplus-12v-24v-48v-800va-3kva

 

Current setup:

50A cord to transfer switch (ts)

Generator to ts

ts to EMS

EMS to inverter which has a pass through

big items which have been wired to run off the inverter: one AC unit, res refrig, microwave

 

I know having the PI EMS after the ts is unconventional, but has caused no problems so far when on the generator

 

Where I will be in the next few months is:

50a cord to EMS to inverter

Generator to inverter

the Victron unit has its' own ts built in

 

But I still am wondering if the EMS will kick out before the inverter has a chance boost the current

[Yarome]

I would agree that it would be more ideal to have your EMS wired solely on the 120v shore power line prior to your transfer switch.

 

Regardless though.. to your question.. if you do indeed have a "hybrid" type pass through inverter then your EMS will not interfere in any way with it augmenting your 120v load demand/supply up to the maximum capacity of your power distribution panel.

[Yarome]

But I still am wondering if the EMS will kick out before the inverter has a chance boost the current

 

We must have been typing at the same time.

 

No. You should be good to go.

[oldjohnt]

fly2low, Thanks for the info, now that we all

 

1) Know what Inverter you have,,,,,,,,,,,

2) Know that it indeed synchronizes with the utility as we didn't know before,,,,,,,,

3) More info how its wired,,,,,,,,,,,

 

We can proceed.

 

According to the specs available

 

Uninterrupted AC power (UPS function)
In the event of a grid failure or shore or generator power being disconnected, the inverter within the Multi is automatically activated and takes over the supply to the connected loads. This happens so fast (less than 20 milliseconds) that computers and other electronic equipment will continue to operate without disruption.

 

It "SUBJECT TO" how fast the EMS responds, should work to boost the power if and when needed and the EMS should allow such and NOT trip PROVIDED THE EMS DOENT TRIP PRIOR TO 20 MILLISECONDS WHICH I DOUBT............ However, if the EMS were so sensitive or fast that it might drop out BEFORE 20 milliseconds PLUS the voltage dropped below the EMS threshold before the Victron could raise it orrrrrrrrrrrrrr was so bad the Victron couldn't make up the difference subject to too big of a load, IT COULD STILL DROP OUT but it looks like its fine, but absent the actual EMS specs and response time I cant say for 100% sure

Again based on the specs it appears its indeed a pass through type of Inverter that automatically synchronizes and can "augment" your Uitlity OR Genset power if needed and it appears it will do it so fast hopefully the EMS will not see it and allow its operation BUT NO WARRANTY I GAVE IT A FAST READ.

 

LOCATION OF EMS

 

In general Id prefer the EMS to be ahead of the transfer switch so you're only managing the Utility and NOT the Generator which may or may not (depends if Inverter style or not) maintain a perfect accurate steady frequency PLUS subject to generator size and load, could tend to sag more then the utility if an AC starts up and between those two there's some chance of a nuisance trip ??????????????

 

HOWEVER if that Inverter can maintain voltage as fast as it appears and your genset maintains a good frequency, I can see how where you have it is working as it can raise genset or utility voltage. I guess if its working and you're satisfied with it IF IT AINT BROKE DONT FIX IT LOL

 

Its so much easier to help once we know what you have, but I still cant say for 100% unless I had all the EMS specs and response times etc etc

 

GO FOR IT

 

John T

[fly2low]

Thanks all for your input. I have not had any issues, so far, so you guys are probably correct. If the EMS ever kicks off the power before the Victron can do its' thing I will let you know.

As for the EMS being after the transfer switch, I bought the EMS and took it to the local repair place I use to have it installed. I was having a bunch of other work done at the same time. I had told them how I wanted to have it hooked up (before the ts) but ended up with what I have. It has not been a problem, but will be rectified when I eliminate the current ts and use the ts function of the Victron.

[oldjohnt]

flytolow, I may be mis reading or mis understanding some of this butttttttttttttt when you state

 

"but will be rectified when I eliminate the current ts and use the ts function of the Victron" YOU SURE YOU STILL DONT NEED YOUR PRESENT TS??? Or did I mis understand what you said?? I don't think you can "eliminate the current Transfer Switch" as you stated.

 

I have a question: I was thinking the Transfer Switch function of the Victron switched between Utility (or Genset if TS is set there) orrrrrrrrrrrr Battery (which it Inverts to AC) ????? IE The utility or generator enters it as a pass through device (with sync ability) and as long as the utility is sufficient you're charging the batteries and not using their energy to invert into AC,,,,,,,,,,,,,,,,, but if the utility or genset fails its TRANSER FUNCTION kicks in Inverter power within 20 MS so were hoping the EMS never senses a problem.

 

HOWEVER your normal two INPUTS (Genset orrrrrrrrrr Utility) Transfer Switch is what switches one of those two INPUTS to your OUTPUT which feeds your panel via the EMS and Victron.

 

I am under the impression (may be dead wrong) the Victrons Transfer Function is ONLY between Utility/Generator orrrrrrrrrrr Battery and Utility/Generator passes through (with sync ability) it so it can boost or provide power if either fails??? BUT YOU STILL NEED THE ORIGINAL GEN OR UTILITY TS to decide what feeds your panel and EMS and Victron

 

HELP ME OUT HERE I'm cornfused lol

 

John T I told you I'm toooooooooo longggggggggggg retired from engineering and rusty on this but hey I'm trying my best to help

[fly2low]

the Victron has separate inputs for the generator and for 50A AC line, and will switch between them. It will also track long term usage of the two, as well as solar input. Right now I am only using one of the inputs - coming from the ts.

[fly2low]

and to be clear, thanks to all who responded. When I was typing the original question, I was hoping a few specific people would give me their beast WAG - and you did. Thanks, This is a great site

[57becky]

You should NEVER sync a power supply to a utility source. If the utility source failed, you would be backfeeding the utility and could get someone killed. That is why a genset installation is isolated from the utility with an isolation switch, that can only connect to either the utility or the genset, but NEVER to both at the same time. I know of at least two of my fellow utility workers that died due to incorrectly wired generator installations.

[oldjohnt]

the Victron has separate inputs for the generator and for 50A AC line, and will switch between them

 

flylow, that settles the issue then no problem.......................once we have alllllllllll the info it makes our job so much easier lol If the Victron already has its own Generator/Utility transfer switch in addition to the Battery/Inverter Transfer Switch, sounds like you're good to go if its as you explain it. Of course I'm sure it has all the necessary safety features and lock outs so you cant backfeed the utility as 57 becky warned of below

 

PS you know that aside from voltage sags or frequency problems that might nuisance trip an EMS when connected to your generator or inverter, there's the whole serious issue of open grounds or open neutrals and Neutral ground Bonding an EMS also monitors and which MUST be correct when fed by a generator or inverter BUT IF YOUR EMS IS WORKING, YOUR SOURCES AND ESPECIALLY TRANSFER AND GROUNDING AND BONDING MUST ALL BE CORRECT so heck maybe just leave it where it is ???????????????????

 

John T

[oldjohnt]

57 becky

 

"You should NEVER sync a power supply to a utility source. If the utility source failed, you would be backfeeding the utility and could get someone killed. That is why a genset installation is isolated from the utility with an isolation switch, that can only connect to either the utility or the genset, but NEVER to both at the same time. I know of at least two of my fellow utility workers that died due to incorrectly wired generator installations."

 

CORRECT you NEVER create a situation whereby a Generator might in any way possible backfeed the utility. That's the purpose of proper transfer switching which is constructed mechanically and electrically such that the generator can NOT be connected to the utility. When I use the term "synchronize" I'm talking about matching the 60 cycle sources at the same time and frequency.

 

As you would expect, trained professional linemen and utility companies are well aware of such a hazard and shunt out or disconnect such that even if some "dude" is backfeeding they don't get electrocuted. It may fry the dudes generator if the utility feeds it however YIKES LOL

 

GOOD SAFETY CONSIDERATION, thanks for posting

 

Keep safe and take care

 

John T

[Yarome]

I would be very careful to ensure exactly which model you have and it's capabilities. The one you linked to (multiplus's) is a single AC input w/primary and aux AC output (dual outputs). Switching is limited to pass through current -or- inverter output only (as John pointed out) with dual AC outputs (not to be confused with dual inputs).

 

As far as I recall.. the quattro's are the only ones that have dual AC inputs (in the Victron line-up that is). Just for clarification for anyone else wanting a similar setup.

[oldjohnt]

Yarome, were both on the same page and trying to cover alllllllllll the bases it looks like, but sitting here I just cant say for sure how his device works. I generally take people at their word if I cant prove otherwise. I think all would agree if his unit DOES NOT have a built in proper Generator/Utility INPUT Transfer function he still needs his old one HOWEVER if it does as he seems to indicate ???? he doesn't........... Like I always tell my adult kids when they ask questions, sure I know SOME things, but I don't know EVERYTHING LOL

 

John T

[fly2low]

Yarome

You are correct.

https://www.victronenergy.com/upload/documents/Quick-Install-Guide-MultiPlus-12V-24V-48V-3000VA-50A-EN.pdf

That and rereading the manual shows there is only one input.

So I won't me making any changes.

I went through so many manuals and schematics when I was working with AMSolar to configure my system that I could not keep them all straight.

Sorry for the confusion Oldjohnt

 

the Victron equipment is pretty amazing, and I am still trying to fully comfortable with everything

[Yarome]

Victron equipment is pretty amazing

 

Yup! The multiplus is some good gear, that.

 

Personally, I prefer your current setup.. an independent mechanical TS over an integrated inverter/charger dual source unit. TS's are a common point of failure. If one were to let the blue smoke out, it's a simple 5 minutes replacement vs. having down time for a costly inverter/charger repair.

[Jack Mayer]

Actually, transfer switches are very reliable if MAINTAINED. Most have a 100,000 cycle mean point of failure. BUT if the wires are not tightened in the lugs annually they can have issues. Nevertheless, I think it wise to have separate transfer switches if you have the space.

[oldjohnt]

"That and rereading the manual shows there is only one input.

So I won't me making any changes."

 

Sounds like a good easy simple plan leaving the (now that we know its still needed as I first suspected) existing Transfer Switch in place wired as is CONGRATULATIONS. Now, if the Victron is performing and switching fast enough (Utility or Genset Input versus Battery/Inverter when needed) such that the EMS don't respond and the Generators voltage and frequency isn't tripping the EMS HEY IT SOUNDS FINE AS IS WHERE IS............If the Generator ever causes undesired EMS response simply move the EMS over to the utility.........It must be doing good to maintain frequency and not allow excess voltage sags on AC start ups. YOUR VICTRON AND GENERATOR SOUND LIKE THEY ARE QUALITY BUILT.

 

Good catch by Yarome

 

John T

[Yarome]

Actually, transfer switches are very reliable if MAINTAINED. .

 

... and you implement good energy switching/load practices... they ARE very reliable. I didn't mean to imply that they have a high failure rate. Just that it's not uncommon for a transfer switch to fail under real world use.. granted.. generally due to prolonged abuse. Ie., genset + shore power "on" switching, "load on" switching, under-powered genset "dropout" under excessive load, etc.

[oldjohnt]

I gotta agree with Yarome and Jack on this one. Good discussion on how switching under "load" is more harmful then switching under "no load" conditions. If there's no load current there's no ARCING at the switching contactors which produces heat and resistive carbon and possible burning and pitting of the contacts ALL OF WHICH DEGRADE THE MATERIAL and can even cause them to stick/weld closed. If there's a load (especially high current) present right when a TS switches CLOSED, you will get the higher initial inrush current surge and an arc when contact is made. Similar, if there's a load (especially inductive like a motor or transformer) when a TS OPENS, you again get arcing. In a "perfect" world you would NOT want a situation where a heavy load like AC draws current as the TS switches CLOSED, and you would shut off heavy loads like the AC before the TS switches OPEN.

 

Its switching UNDER LOAD that can cause premature TS failure. Switching under load (regardless if opening or closing) is so much more harmful then no load conditions due to arcing and heat and carbon and burning/pitting.

 

John T