powercut during switching

J

jan131109

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Location
spain
Occupation
electrician
hello , i have a solar installation with battery. In the evening when battery power take's over, it happens with a short powercut . This , i thought , could be solved if i place a capacitator in the circuit. Would this help ? and if so , what type ? the load is around 10Kw.
thank you.
jan
 
jan131109 said:
hello , i have a solar installation with battery. In the evening when battery power take's over, it happens with a short powercut . This , i thought , could be solved if i place a capacitator in the circuit. Would this help ? and if so , what type ? the load is around 10Kw.
thank you.
jan
Click to expand...
A capacitor cannot bridge AC.
 
It's not clear what's supply what when..... batteries, solar, is there utility power? How are things connected. If a bog-standard mechanical transfer switch is in there, there will be a short blip.

Please tell us a lot more about the system, if nothing else, a one-line diagram would help.
 
it is a hybrid system , so conected to the grid , and when PV power is not enough , battery kicks in. it is then when i get the ( very ) short power cut.
the load is high ( around 10Kw ) . i was just looking for .....? something that could prevent the powercut during the switching ( milli second )
( my apolagies for the many spelling mistakes, english is not my native language)
 
What is doing the switching? If it's a mechanical break-before-make switch, there is going to be a "powercut"*.
Is the battery-powered inverter always supplying the load (as in an online UPS)?

Assuming 50Hz, a half cycle is only 20ms, and most equipment won't notice it. (what is the equipment being supplied?)

*"power cut" often implies the incoming grid supply is interrupted for a relatively long time, if the power only stop for a second or less, we'd call it an brief interruption
 
it is the invertor that makes the switch , and i supose , the machanics off that internal switch is too slow ? the load is a , frozen yogurt shop, and that machine ( alone ) is already 6Kw , most of the load is indeed not affected , only that machine has to reboot every time and that takes a minute.
and indeed , a power cut , might be a wrong choice of word , but for a milli second there is no power . that is why i thought that a capacitator might cover that .
many many thanks for your answers ! really apreciate it !
 
Gak, yogurt and soft-serve ice-cream machines have some of the worst control systems! Seems as if you look at them funny they throw an error code or just reboot.

I'd say the problem really rests with the machine's design, but after that it's onto the inverter (model number, please; it's always helpful to include as much info as possible). You may find out that a machine reboot is cheaper in the long run than any equipment changes, but it's hard to tell at the moment.
 
Sounds like the problem is particularly sensitive electronics in the machine. Not much you can do other than put the controller on a UPS. Then the UPS will cover the small switch over gap.
 
For a grid connected system, there should be no power cut. Pvnoob may be correct that your machines are usually sensitive to something related to the inverter output. It's also possible something else is going on. The solar system installer or the machine manufacturers would probably the best people to help.
 
jaggedben said:
For a grid connected system, there should be no power cut. Pvnoob may be correct that your machines are usually sensitive to something related to the inverter output. It's also possible something else is going on. The solar system installer or the machine manufacturers would probably the best people to help.
Click to expand...
Even for grid connected systems, switching to backup mode when disconnecting from the grid is going to have a very small gap. The inverter has to change from a current source to a voltage source after the disconnection and that takes a finite amount of time. It's small and most electronics run off a DC power supply that can ride through that short gap.
My guess here is that the machine controller does not have sufficient ride through capability and it is getting a voltage droop and resetting. Probably the controller does not have a separate power cord from the rest of the machine that could be plugged into a UPS leaving few options. Putting the whole 6kW machine on a UPS would be expensive.
 
pv_n00b said:
Even for grid connected systems, switching to backup mode when disconnecting from the grid is going to have a very small gap. ...
Click to expand...

I didn't hear him saying that the system is switching to backup mode. He said 'in the evening', which corresponds to the sun going down but not to a power outage. But I guess his description is still a bit vague.

In a grid connected system, it should always be possible for the batteries to 'take over' the grid tied operation when the sun goes down, without a power interruption. (Whether or not the system is also capable of providing backup power.)
 
jaggedben said:
I didn't hear him saying that the system is switching to backup mode. He said 'in the evening', which corresponds to the sun going down but not to a power outage. But I guess his description is still a bit vague.

In a grid connected system, it should always be possible for the batteries to 'take over' the grid tied operation when the sun goes down, without a power interruption. (Whether or not the system is also capable of providing backup power.)
Click to expand...
Yeah, it's vague. If it's a grid tied system and the grid is up then switching between PV and battery will be seamless. But OP says there is a power cut. This is not a description of any PV+BESS grid tied system I am familiar with, "... connected to the grid , and when PV power is not enough , battery kicks in ...". To get the gap they are describing the grid has to drop and the hybrid inverter has to shift from grid tied mode to island mode.
 
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