SWEA GT Inverter. Standby consumption

[G8GMU]

Just having put a power meter into to the output to see how much my SWEA 250 Watt GT invertor gentrates. The power meter showed 31 Watts. Turning off the DC input to the inverter the meter read 28 Watts having cleared it between readings. Surely it does not consume 28watts from the grid on standby. The meter in use is a plug in device between the mains output plug & socket type HO 1569.



Can someone who has on make  test to tell me what power their SWEA 250 watt inverter take in standby.

[Justme]

Thats why the roof mounted choc tea pots actually COST money to have on the roof cos they use more than they make.

Justme

[Alan]

If you use a rotation detection relay that makes above a certain R.P.M. you can get this to energise a solid state relay on the grid inverter A.C. side so that you have zero stand by power until the turbine is spinning at a speed where useful power can be used.
Another way is to use a PIC microprocessor to detect either D.C. volts generated by the turbine or use an input to detect the alternator frequency. Either way when useful power is available then energise the solid state relay to turn on the grid inverter. The PIC approach is better because it can be used for switching various loads on the D.C. side if you do not want to export power.

Regards

Alan

[Justme]

If you do that Alan wont you have a hot / cold start problem?

IE

Hot start with inverter watching the grid ready to pounce as soon (in a small time frame) as power is made
Compared to
Cold start where inverter needs to sync with grid run through all its start up tests & checks before running a hot start?

Sure I read some place that the hot sync time was a Heinz let alone a cold start.

Would be better to RUN the inverter on a battery charged from its own power but MONITOR / sync to the grid.

Justme

[billi]

still  28 watt would mean  about 240 kwh a year 

In that test in holland  of small windturbines  the consumption of the installation was no were near that 240 kwh

look out for  " Verbruik in kWh "

http://kreeft.zeeland.nl/zeesterdoc/ZBI-O/ZEE/ZEE0/8012/801257_1.pdf

Billi

[RichardKB]

I would be suprised that it is that much, it is more likely that your power meter is inaccurate at this level or power factor. They are usually in the range of 5W.

Rich

[Justme]

I would be suprised that it is that much, it is more likely that your power meter is inaccurate at this level or power factor. They are usually in the range of 5W.

Rich

I think Navitron sell one that is good for low wattage. Or test a known low watt item & compare to test results.

[G8GMU]

HI,

I have done calibration tests with 2 diffrent mains filament lamps. The reading is within 12%
of the lamps' rating.

Have checked the current & voltage with an accurate AVO8 this also confirms the
current and voltage indicated by the plug-in Wattmeter within a very few percent, given that the AVO will take no account of power factor. Just a simple VxI calculation.

It seems as if the inverter is simply not going into 'sleep-mode' when there is no DC input.


I am of course grateful for all suggestions  with this problem.


Many thanks

 G8GMU

[RichardKB]

To test your meter try using an older 100W switch mode psu with about 20w DC load on it and see what the meter reads.

Rich

[SWEAEUROPE]

Hi,

This is MAri van der HEijden CEO of SWEA EUROPE BV manufacturer of the SWEA grid tie inverter  UWT-I-250  Starter kit or UWT-I-250 Extension kit.
There are many quoestions about the Power taken out of the grid when the inverter do not give power to the grid.
Many see 28 Watt on the watt meter. Pls read below explanation.
 

I can tell you that the inverter consumes only 0,375 Watt when the solar panel(s) or the wind turbine gives no power.

When you use a standard watt meter  you see 28 Watt on the screen. But this is a wrong measurement.

Imagine that you  put a 28 watt globe into a small box. This box must become hot because the lamp has to get writ of his heat.

When you connect the inverter and when the invereter is in stand by mode  THE INVERTER STAYS COOL.

This means that there is NO power dissipation in the grid tie inverter.

The 28 W  we call  “BLIND POWER”

The inverter has to measure the grid because the sine wave must be in line when the inverter connects the turbine or the solar panel power  to the grid.

At that moment ( half sine wave ) the inverter takes  power from the grid and the other half sine wave  the inverter gives the power back to the grid minus the 0,375 watt power lost.


 I hope it is clear now.  When there are still questions pls feel free to ask. P

[rienm]

The inverter makes use of the power from the DC input, not from the grid. The only power taken from the grid is a very small current in the measurement divider and resistors for the net synchronisation of the output circuit.

The instrument that you used to 'measure' the power used by the SWEA UWT-I250 is probably one that is not calibrated very well. It is not able to measure the phase of the current accurately, which leads to large faults.
The actual power taken from the grid with these inverters is less than 0.4W. The measured capacitive current is about 0.12A. This is mainly the current flowing through the filter capacitors ('X capacitors') and does not represent the real power.

Always use a reliable and calibrated instrument to do good measurements.

Rien

[baker]

Just having put a power meter into to the output to see how much my SWEA 250 Watt GT invertor gentrates. The power meter showed 31 Watts. Turning off the DC input to the inverter the meter read 28 Watts having cleared it between readings. Surely it does not consume 28watts from the grid on standby. The meter in use is a plug in device between the mains output plug & socket type HO 1569.



Can someone who has on make  test to tell me what power their SWEA 250 watt inverter take in standby.

I have a windy boy 6000a it uses 8w on standy

[Other-Power]

Could always use a mechanical timer if its on a solar system?

[guydewdney]

the aurora 3.6kw inverter uses about 40 watts...