inverter generator match [RE-wrenches]

[jberdner at sma-america.com]

Dear Wrenches:

One of the other fundamental problems here is the power factor of the
inverter while charging.
A low power factor on the inverter/charger makes it very difficult for low
cost generators to deliver any energy to the charger.
This is one of the reasons UL 1741 requires a PF of > 0.85 (I think this is
the value).

If you are doing phase control with an SCR it is a cheap way to build a
charger but this typically creates a bad power factor.
If anyone has a Fluke 42 or equal (homepower guys?) take a reading on the
inverter/charger while charging.
This is an area that has not been given much attention but it will likely
become more significant as other inverter options become available.

In general, a charger with a higher power factor (1.0 is as good as you can
get) will have less problems with inexpensive generators.  A charger with
low power factor will need more duct tape and bailing wire to work with
inexpensive gen sets.
Adding resistive load (light bulbs) improves the total power factor and
helps the generator to make power at the time when the charger is asking for
it.

If you have any questions or I can be of any further assistance please do
not hesitate to contact me.

Best regards,

John Berdner

SMA-America, Inc.
20830 Red Dog Road
Grass Valley, CA  95945
Tel: 530.273.4895
Fax: 530.274.7271


-----Original Message-----
From: Carl Emerson [mailto:freepower at freepower.co.nz]
Sent: Thursday, February 15, 2001 12:25 PM
To: RE-wrenches at topica.com
Subject: Re: inverter generator match [RE-wrenches]


An other angle on this issue...

We have found that some Japanese gen. sets have very poor alternators, and
/or
very poor voltage regulators.
Typically we avoid any capacitive discharge voltage regulators and make sure
that the gen. set has proper electronic voltage regulation.
The two reasons we have found to cause lack of sync once the speed control
issues are eliminated are:
1. Voltage spikes. these are detected by using a meter with data hold and
looking at the AC voltage. Often we find spikes up to 400 volts present,
well
outside the SW voltage window.
Our fix for this is to install a small varister module to cut off voltage
spikes that will trip out the inverter.
2. Poor wave form shape from the gen. set at low load.
Our fix for this is to introduce capacitance. I trick to do this easily in
the
field is to simply plug in a long AC lead into the gen. set in parallel with
the lead to the SW.

This in many cases has eliminated the need to run a load and waste valuable
power.


Carl Emerson
Manager
FREEPOWER LTD.  "Harnessing Natural Energy"  Auckland, NEW ZEALAND.


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For info contact list moderator by email:
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____________________________________________________________
T O P I C A  -- Learn More. Surf Less. 
Newsletters, Tips and Discussions on Topics You Choose.
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