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MECC Alte ECP28-S/4 alternator connections


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  #1  
Old 08-31-2012, 12:01:52 PM
stakstak stakstak is offline
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Question MECC Alte ECP28-S/4 alternator connections

Hi
This alternator is in Australia (240V).
It is regulated by a Mecc Alte SR7/2G and coupled to a Perkins Series 100 diesel engine.
It will be the backup for the house solar system.

What is the best way to connect the 2 AC wires from the house switchboard?

3 Phase Series Star option (as it came from the supplier):
L1(1), (2-3), N(4-8-12), L2(5), (6-7), L3(9), (10,11).
Where do the 2 AC wires from the house switchboard connect?

Single Phase Double Delta option:
L1(1-10), N(2-3-5-12), L2(7-4), (6-9), (8-11).
Where do the 2 AC wires from the house switchboard connect?

Series Delta option:
L1(1-12), (2-3), L2(4-5), (6-7), L3(8-9), (10-11).
Where do the 2 AC wires from the house switchboard connect?

Mecc Alte
Type: ECP28-S/4
Phase: 3
RPM: 1500
Ins. Cl.: H
PF: 0.8
KVA: 17
V.: 115/200/230/400
A.: 85/49.1/42.7/24.5
Hz: 50
IP: 23

Thanks
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Old 08-31-2012, 05:25:57 PM
armandh armandh is offline
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Default Re: Mecc Alte ECP28-S/4 alternator connections

please get competent qualified professional help
I am deadly serious
it is too easily done dangerously wrong
otherwise let us know where to send the flowers
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Old 08-31-2012, 06:13:22 PM
stakstak stakstak is offline
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Default Re: Mecc Alte ECP28-S/4 alternator connections

Thanks Armandh
No intention of pushing up daisies any time soon, although, cremation is on the cards when it comes to all things electrical.

Please allow me to give further info-

The previous alternator was a Mecc Alte EC28-LB/4 with a Single Series Delta connection (Active connected to L1(1-12) and Neutral connected to L3(8-9)).
It ran for 20 years.
I believe an incorrect AMP potentiometer setting on the SRG/2G, combined with a large load, contributed to it's demise.
I could connect the new ECP28-S/4 the same way, but, was wondering if a Double Delta connection with Active connected to L1(1-10) and Neutral connected to L2(4-7) would be better.

Thanks
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Old 09-01-2012, 07:41:18 AM
Jim Rankin Jim Rankin is offline
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Default Re: Mecc Alte ECP28-S/4 alternator connections

Either the double delta or series delta will work well. I believe there will be no difference in performance as long as you use the two lines of series delta that the voltage regulator is sensing. That way the regulator will respond to the load more directly.

You will need to ensure that there are no neutral to earth bonds in the generator other than the one you make by earthing one line. In the North American scheme, the midpoint of both the double delta and one side of the series delta would be bonded to earth so 120 volts would be avaliable. Since your generator is labeled 50 hz I doubt there are any bonds like that.
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Old 09-01-2012, 08:48:06 AM
stakstak stakstak is offline
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Default Re: Mecc Alte ECP28-S/4 alternator connections

Thanks Jim
The old alternator's regulator (Mecc Alte SR7) sensing connections-
No.4 green to L1(1-12) and No.5 black to (2-3).
Are you suggesting this was incorrectly setup 20 years ago?
The two series delta lines used were L1(1-12) and L3(8-9).
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Old 09-01-2012, 10:11:46 AM
armandh armandh is offline
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Default Re: Mecc Alte ECP28-S/4 alternator connections

since you are looking for 220V 50Hz 1Ph
not the split 240/60 usually found in US
either double delta, series delta, or parallel zig zag should work equally well
but series delta gives the opportunity for 3 Phase use if needed


I suspect that you are picking up the house bonding point
if so the output should not be bonded at the generator
but be isolated from the generator frame
which would have separate earth connection

if the output must be bonded at the generator
there should not be any additional bonding later in the distribution

local rules and codes must prevail
the link shows why there should be seperate earth and only one bond [in your case 220V]
http://www.smokstak.com/forum/attach...7&d=1298646020

Last edited by armandh; 09-01-2012 at 10:25:53 AM.
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Old 09-01-2012, 11:20:21 AM
Jim Rankin Jim Rankin is offline
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Default Re: Mecc Alte ECP28-S/4 alternator connections

The old generator must have had a 110-120 volt regulator sensing/supply. Only way it could have worked connected across 1 and 2.

While it probably was better able to regulate on your 220 voltage/connection than it would have on a 120-0-120 like we have here, I am surprised that the manufacturer configured it that way. Usually that kind of regulator is used where the generator is reconnectable for 110-120 only.

As you have probably gathered, you do not want to connect your house to the generator while it is connected series star 230/400 3 phase unless you need only a (very temporary) limited amount of power ~6kva because you will only be able to load 1/3 of the generator's windings. Also important to make sure the load is applied to the same phase as the regulator supply. House would be connected to any line and neutral to deliver 230V single phase.

If you have 2 neighbors who also can use ~6 kva, you can use the series star to supply the group, connecting each neighbor to a line and all using the earthed neutral.

You don't mention if the tag has any information about de-rating the generator output when supplying single phase. The standard 3 phase reconnectable alternator is derated by 1/3 when supplying only 1 single phase load unless it is an optional higher capacity model which essentially has more copper and iron to last while supplying the overload that the single phase will present if you attempt to pull full kVA rating on it.

Could be what happened to the last one?
The other connections use all 6 coils of the generator and balance the current and magnetic flux much better than connecting single phase to a 3 phase Y. With our split phase system here, we have the additonal task of balancing our 120 volt loads between the two lines.

This didn't come out in the right order.............
Just to reiterate......................................... ........
When connected for double delta, series delta or parallel zigzag, the current and flux in the generator are balanced, but the single phase kVA is still derated by 1/3 unless the manufacturer says otherwise.

Stick with 42.7 amps to be safe.
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Old 09-01-2012, 06:21:50 PM
stakstak stakstak is offline
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Default Re: Mecc Alte ECP28-S/4 alternator connections

The old alternator's regulator (Mecc Alte SR7) sensing and supply connections-
Sensing- No.4 green to L1(1-12) and No.5 black to (2-3).
Supply- I believe the alternator is equipped with an auxiliary winding for regulator supply, so 2), below, would apply.

The manual states-

Supply: There are two possibilities.
1) The supply coincides with the sensing. In this case the SR7/2 supply-sensing should be connected to terminals 4A and 5 (in the case of three- phase generators, terminal 5 is normally connected with the star point). Terminals 3A and 4 should be connected to each other in such a way that the supply is also the sensing. This connection is necessary when the generator does not have auxiliary winding for supplying the regulator.

2) The supply and sensing are separate. This is the case of a generator equipped with auxiliary winding for regulator supply. Supply is always connected to terminals 3A (or 3) and 5C (or 5, 5A, 5B) of the regulator.

In both these cases (1 and 2) the SR7/2 supply can vary from 80 to 270 Vac. But it should be noted that terminals 2 and 3 should be bridged for supply with voltage between 80 and 160 Vac, while the same terminals should be left open if the voltage is between 160 and 270 Vac.



I don't know who setup the generator connections. It was before my time. I came along about 7 years ago.

I have no intention of connecting the house to the generator while it is connected series star 230/400 3 phase, but, thanks for the info. I'll either connect it the same as the old alternator- Series Delta or a new arrangement- Double Delta. At the moment my main concern is if I go with copying the old setup -Series Delta, the regulator connections are correct.

The Mecc Alte supplier said the following about single phase output-
Model: ECP28-S/4 17KVA 3f 415V (re connectable to 11.4KVA 1ph 240V).
This is inline with what you thought as 11.4KVA is about 1/3 less than 17KVA.
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Old 09-01-2012, 08:37:32 PM
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Default Re: Mecc Alte ECP28-S/4 alternator connections

Quote:
Originally Posted by armandh View Post
...series delta gives the opportunity for 3 Phase use if needed
I suspect 3 Phase may have been needed for high load machinery when the house was built 20 years ago, and that is why they went with Series Delta. The house is steel framed and the fence is steel, so, a lot of cutting, grinding and welding.

Quote:
Originally Posted by armandh View Post
I suspect that you are picking up the house bonding point if so the output should not be bonded at the generator but be isolated from the generator frame which would have separate earth connection
Coming from the house are 2 load wires. One went to 'A' [marked in pen next to terminal L1 (1-12)] the other went to 'N' [marked in pen next to terminal L3 (8-9)].

There is also an earth/ground wire that is connected from a 20 yard metal pipe to the earth/ground point inside the terminal box on the alternator. This pipe runs underground from the generator shed to the house. Inside is a plastic conduit pipe which carries the 'A' and 'N' wires coming from the house. The house is earthed/grounded independently. I gather the metal pipe functions as an independent earth/ground point for the generator and is added insurance against native animals around here that love to dig. This place is in the bush and off the grid. Many wombats, bandicoots, potaroos, wallabies etc.
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Old 09-01-2012, 09:10:18 PM
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Default Re: Mecc Alte ECP28-S/4 alternator connections

Attached is a photo of the terminal board.

The bright yellow/green wire comes from the previously mentioned metal pipe.
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Name:	Mecc Alte EC28LB4 Terminal Board.jpg
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Old 09-02-2012, 06:07:44 AM
armandh armandh is offline
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Default Re: Mecc Alte ECP28-S/4 alternator connections

off grid is the critical info

as long as the N is bonded to earth ground in one place all is good.
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Old 09-02-2012, 12:02:29 PM
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Default Re: Mecc Alte ECP28-S/4 alternator connections

I'm thinking of going ahead and use the old alternator's configuration- Series Delta, on the new alternator.

The new regulator/alternator's sensing cables setup as they came from the manufacturer-
  • No.4 green, crimped and plastic heat shrink tubing sealed to alternator cable 3
  • No.5c black, crimped and plastic heat shrink tubing sealed to alternator cable 4

My question is, if I leave the sensing cables like this will they perform correctly?

The Series Delta would look like this-
'A' connected to L1(1-12), (2-3 & green sensing cable), L2(4 & black sensing cable-5), (6-7), 'N' connected to L3(8-9), (10-11).

Your opinions are greatly appreciated.
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Old 09-02-2012, 07:51:08 PM
armandh armandh is offline
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Default Re: Mecc Alte ECP28-S/4 alternator connections

for series delta

what voltage is the new regulator supposed to sense

if half voltage connect to N and the mid point of the series coils going directly to the L1 [220V] hot lead.

if 220 connect to N and L1

if the regulator is configurable to either voltage use the 220

the regulator is going to try and develop the required voltage it is set for
and should be connected to coils connected to produce that voltage as well

Last edited by armandh; 09-02-2012 at 08:02:55 PM.
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Old 09-02-2012, 09:35:10 PM
Jim Rankin Jim Rankin is offline
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Default Re: Mecc Alte ECP28-S/4 alternator connections

I would configure it for 240 volts (no jumper between 2 and 3 of regulator) and wire it across L1 and L3(your neutral).

About the regulator supply, are there wires connected from the generator stator to regulator terminals as in this quote from the regulator manual?
"Supply is always connected to terminals 3A (or 3) and 5C (or 5, 5A, 5B) of the regulator. "

If not, then you would have both sensing and supply from the same L1 and L3(N) connection by
"Terminals 3A and 4 should be connected to each other in such a way that the supply is also the sensing. This connection is necessary when the generator does not have auxiliary winding for supplying the regulator."

If there are auxillary winding connections to Terminals 3 and 5, then my assumption is that they would stay in place.
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Old 09-03-2012, 12:50:43 AM
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Photo Re: Mecc Alte ECP28-S/4 alternator connections

Thanks Jim
The supply wires on the new alternator are connected from the stator (I think the auxiliary winding) to 3A and 5 on the regulator.
My concern is with the sensing wires from the regulator in a Series Delta configuration. If I leave them as they came from the manufacturer, they will be sensing across 3-4 in the stator.\

Here is a diagram from the regulator manual. This is the way the new alternator is setup.
(PD = Parallel Device, and is not relevant to my alternator)
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Old 09-03-2012, 01:09:02 AM
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Default Re: Mecc Alte ECP28-S/4 alternator connections

Here's a pdf, the previous jpg didn't work.
SR72G.pdf
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Old 09-03-2012, 05:12:11 AM
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Default Re: Mecc Alte ECP28-S/4 alternator connections

Understood armandh, thanks.
So the previous regulator sensing setup was incorrect.
It was sensing across L1(1-12) and (2,3).
As the generator powers an Australian house/batteries when the batteries are low, the regulator would have been set at 230VAC (or even 240VAC).
Looks like it was connected up to sense only half of that.
Do you know what impact that would have had on the system?
I'm also trying to patch together why the old alternator failed.
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Old 09-03-2012, 08:08:17 AM
Jim Rankin Jim Rankin is offline
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Default Re: Mecc Alte ECP28-S/4 alternator connections

The regulator being set up to sense across 110 volts might have something to do with the auxillary winding (or maybe not?). If you do not want to change that factory setup, then simply change your house neutral connection from L3 like it was on the old generator to L2 on the new generator.

That way the load is across the same winding that the regulator is sensing from. (Even though it is sensing only 1/2 of the winding). Still works and will be better than having it sensing a completely different phase from where the largest load is applied.

I haven't seen anything in what you have posted about the old generator setup that would indicate why it failed other than perhaps an overload?

What did happen to the old one? Stator burned? exciter bad? regulator? Auxillary winding? Rotor?
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Old 09-03-2012, 09:52:07 AM
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Default Re: Mecc Alte ECP28-S/4 alternator connections

Thanks Jim
What you said makes alot of sense (pun intended!)
Connecting the house 'Neutral' to L2 might be a good solution.
If it was connected that way there is also a control module on the wall and settings might need to be changed there too.
I'm trying to find the simplest solution.
If the old setup was sound, I'm happy to mimic it's configuration.

Yes, I believe the old alternator ultimately failed from an overload. A short history....

The generator had been temperamental at starting ever since I came along 7 years ago.
It has only been started, on average, about once a month (for a few days in a row) for the past 12 years, as no one was living here full time up until this year.
We thought it was the diesel engine or a poorly charged battery.
A month ago I decided to investigate in earnest.
I discovered the engine to be fine.
I recall some white smoke and an odd smell (later found out it was burning plastic), coming from the alternator.
Soon it got to the point where it wouldn't start.
I noticed a burned section in the regulator resin that looked like it had been there for a long time, and bought a new one.
Found it difficult getting the AMP pot to function properly on the new regulator so I left it turned fully clockwise believing no harm would arise.
With the generator on (effortless start), and hot shower later (= high prolonged load from the water pump), the excitor melted down throwing pieces of plastic into the rotor and jamming between the rotor and the main stator.
3 rewind shops later for opinions and I was convinced the alternator was toast and cheaper to buy a new one.
So, both stators were fine and the exciter and rotor windings were history.
The guy at the last rewind shop, with many years experience, thought it unusual that the rotor windings burned out before the stators.
He put it down to faulty excitor diodes thus causing the aforementioned melting plastic. Although, he wasn't abreast of the AMP pot situaion.
Maybe the diodes had been dying over the years, causing problem starts.
Maybe a simple tweak of the VOLT pot was all that was needed.
Maybe running the engine at about 1550 RPM as a trial to bring the Hz closer to 50 wasn't such a good idea.
The engine had been running at only about 1440RPM for as long as I had known it.
Many maybe's...

That's the gist, anyway.
Would be interested to know what you can deduce from it.
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Old 09-03-2012, 11:13:24 AM
Jim Rankin Jim Rankin is offline
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Default Re: Mecc Alte ECP28-S/4 alternator connections

Does this generator have a separate starter of does it crank from the generator? If it were to use the generator, there would be a segmented commutator section on the main rotor near the exciter field and rotor. If that is not the case, I cannot understand why it would not want to start with any problem that a new regulator would help. I expect you had a couple different things going on, something in the engine/starter/battery and another problem in the regulator, exciter, rotor.

It is certainly possible there was a failure on the rotor/field or exciter armature/diodes etc that kept the regulator amp'ed up all the time to maintain setpoint voltage.

Also could have had that situation from running low rpm. Although 1440 isn't all that low, it does keep the regulator at a higher load than running at proper rpm. Higher rpm increases the voltage output which results from constant field strength. For example consider a bicycle headlight dynamo, it has a fixed magnetic field and if you pedal faster, the headlight gets brighter.

Most regulators have a under frequency characteristic that attempts to hold the voltage at setpoint as the generator slows down to about 47 hz in your case and then begins to cut the excitation/setpoint voltage in proportion to the hz. This under frequency roll-off feature protects the regulator and exciter from damage when the generator stops under load for whatever reason as well as potentially shortening the duration of the voltage/frequency dip resulting from a sudden increase in load. Without the under frequency roll-off, the regulator tries to keep the voltage up and may end up choking the engine down in a situation where it could recover if the output voltage was allowed to drop and shed some of the load.

It is also possible that the new regulator on the old generator was somehow different than the old one that was burned and exposed the deterioration in the exciter armature, diodes or field. I have a Winco 3 phase brushless alternator which I got with a bad exciter armature. In my case, the exciter armature was balanced by some sort of putty they stuck into the exposed windings. This weight seems to have pushed the windings outward under centrifugal force and damaged them. I had the armature rewound, checked all the diodes and reinstalled the (unbalanced, or at least no putty applied) armature and it works perfectly. I think a bit less attention to balance or a better system of applying weight would have made a huge difference in the longevity of that generator. Fortunately in that case, there was no plastic to melt other than the winding insulation, so damage was limited to the one component.

Any chance there is a new inverter/battery charger installed at the house recently? I believe those things can cause some significant harmonics that increase the heating the generator head experiences far beyond what other "normal' loads cause and above what the amperage being drawn would predict. With a large switch mode power supply on the system, double delta or parallel zig-zag might be a better choice for your connection to avoid harmonics circulating in the series delta. This is something I do not understand, just read some on-line about problems on industrial sytems.
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