Author Topic: generator not making power.  (Read 25869 times)

buickanddeere

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Re: generator not making power.
« Reply #30 on: March 22, 2014, 05:21:18 PM »
  The permanent magnet exciter  should develop an AC output on it's the exciter stator when ever the shaft rotates.  As there are six diodes odds are the exciter is three phase. The PM exciter AC out put should be rectified to DC and supplied to the rotating field at 42VDC.
  As long as shaft speed remains constant. Voltage output of the generator will only vary a couple of percent from no load to full load.
  Sounds like you are going to bypass the built in exciter and just excite from the main output terminals. Works ok except the system may need to be flashed if left sitting for a while. Also if overloaded during motor starts etc. The output voltage will drop lower than if the machine was using the separate PM exciter.

Bison

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Re: generator not making power.
« Reply #31 on: March 22, 2014, 06:17:05 PM »
What caused the diodes to burn out?

 Energizing with a 120VAC patch cord may have ruined the diodes.

Nothing wrong with the diodes, i now understand the patch cord was used as a quick connect to the (missing) control panel.


Bison

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Re: generator not making power.
« Reply #32 on: April 11, 2014, 05:50:45 PM »
I got my SX460 AVR in today,..but it has no how to wire it in" diagram"
I need some expert help again as to how do i connect it up to the generator, which lead goes were?,..what else is needed?
It has 5 pins in this configuration ..F2,F1,6,7,8.

Thanks

Tom

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Re: generator not making power.
« Reply #33 on: April 11, 2014, 07:25:23 PM »
Well based on the info you posted it looks like f1 & 2 will go to the field windings and the other 3 will each go to a leg on the 3ph output.
Tom
2004 Ashwamegh 6/1 #217 - ST5 just over 3k hours.

dieselgman

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Re: generator not making power.
« Reply #34 on: April 11, 2014, 07:59:21 PM »
The Stamford SX460 control uses only single-phase input voltage (either 120 or 240 - jumper selectable)... The included documentation does not identify the inputs and outputs but rather refers you to the generator manufacturer's docs. F1 and F2 are clear enough to be foolproof. I will do a little checking and identify 6, 7, and 8 connections for you unless someone else beats me to the keyboard.

WARNING!!! do not assume you can connect 3-phase inputs to this AVR - it senses voltage via a single-phase input only.

dieselgman
« Last Edit: April 11, 2014, 08:25:13 PM by dieselgman »
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dieselgman

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Re: generator not making power.
« Reply #35 on: April 11, 2014, 08:04:38 PM »
Stamford docs say that voltage sensing terminals are 7 and 8 for the SX460. Do not connect anything to #6.
If you are lacking the AVR docs... you also need to be sure that frequency is properly selected 50hz/60hz via jumper.
select for external voltage trimmer (or none) via jumper.
and select 120 or 240 vac input voltage via jumper.

dieselgman
« Last Edit: April 11, 2014, 08:23:34 PM by dieselgman »
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Tom

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Re: generator not making power.
« Reply #36 on: April 11, 2014, 09:50:09 PM »
Well if there is only 2 voltage sensing wires, where does the field power come from???
Tom
2004 Ashwamegh 6/1 #217 - ST5 just over 3k hours.

dieselgman

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Re: generator not making power.
« Reply #37 on: April 11, 2014, 10:36:56 PM »
Field power is fed through F1 and F2 - these are clearly marked on the AVR.

You simply have two AC leads for output voltage sensing (7 and 8 ) and two field leads for changing the exciter field strength (F1 and F2). That should be all that is needed for the control.

I did not mention the setup procedure... normally have to adjust AVR voltage pot for proper output range as well. If you need the Stamford docs you have to look at the Cummins web site, they now own NewAge AVK Stamford.

dieselgman
« Last Edit: April 12, 2014, 12:19:30 AM by dieselgman »
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millman56

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Re: generator not making power.
« Reply #38 on: April 11, 2014, 11:29:27 PM »
Its a bit confusing if your`e not familiar with AVRs,   the SX460 both senses the output voltage and takes its power from 1 phase to neutral via 7 and 8 terminals, it then feeds a DC output into the exciter field winding via F1 and F2 terminals, it automatically varies the ouput and therefore the field strength based on the voltage sensed at 7 and 8 terminals, this means that when the AC output terminal voltage falls due to an increased load it is automatically raised to the set point voltage and vice versa when a load is removed.     This is the basic operation of an AVR as I understand it.

Mark. 

Bison

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Re: generator not making power.
« Reply #39 on: April 12, 2014, 05:26:23 AM »
Field power is fed through F1 and F2 - these are clearly marked on the AVR.

You simply have two AC leads for output voltage sensing (7 and 8 ) and two field leads for changing the exciter field strength (F1 and F2). That should be all that is needed for the control.

I did not mention the setup procedure... normally have to adjust AVR voltage pot for proper output range as well. If you need the Stamford docs you have to look at the Cummins web site, they now own NewAge AVK Stamford.

dieselgman
[/quote ] Thanks for the replies guys.It all helps but i need a bit more selective info

 I understand that  F1 and F2 are for the exiter leads but which lead goes to F 1 , the + or the - or will either do?
And which of the phase leads go to 7 or 8 or do i hook op 1 phase to 7 and the second phase to 8 or do i use 1 phase and neutral?

The document that came with the AVR mentions the procedure for adjustment of voltage and amperage and hertz selection but not much else.

dieselgman

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Re: generator not making power.
« Reply #40 on: April 12, 2014, 06:50:12 AM »
You can find proper instructions on the Cummins site. It is best to refer to their instructions and safest bet is to have an experienced person handle the setup if you are unfamiliar.

There is a reason that they refer you to your generator wiring rather than giving assumed (less than precise) instructions with the AVR docs. Different sets will be wired in slightly different ways. The functions of the AVR will remain exactly the same though.

Use line to neutral on pins 7 and 8 for 120vac sensing but make sure the sensing voltage jumper is set properly for this voltage. Otherwise you can also use line to line for the high voltage range (if line to line on your set is within range 190-264VAC).

INPUT Voltage Jumper selectable 95-132V ac or 190-264V ac

Use F1 for X or + (DC positive), and use F2 for XX or - (DC negative).

CAUTION

1. Before running generator, turn the VOLTS control fully anti-clockwise.

2. Turn remote volts trimmer (if fitted) to midway position.

3. Turn STABILITY control to midway position.

4. Connect a suitable voltmeter (0-300V ac) across line to neutral of the generator.

5. Start generator set, and run on no load at nominal frequency e.g. 50-53Hz or 60-63Hz.

6. If the red Light Emitting Diode (LED) is illuminated, refer to the Under Frequency Roll Off (UFRO) adjustment.

7. Carefully turn VOLTS control clockwise until rated voltage is reached.

8. If instability is present at rated voltage, refer to stability adjustment, then re-adjust voltage if necessary.

9. Voltage adjustment is now completed.

dieselgman
« Last Edit: April 12, 2014, 06:55:55 AM by dieselgman »
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Bison

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Re: generator not making power.
« Reply #41 on: April 12, 2014, 04:31:23 PM »
Thanks   Dieselgman.
I think with these  instructions i can figure this out now.
It might be a few weeks before i can work on this gen again but i will let you guys know how it panned out.

Happy Easter.
Simon
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