An exact breaker size can not be given because the voltage, and hence the calculation for current, is not given. A transformer shall be protected by an over current device that is not rated at more that 150% of the primary current.
75000va / 480v = 156.25A
156.25A * 125% = 195.31A
I would size the breaker at 200A
3 phase 480v 20amp ckt
150 amp
The main breaker will have marking indicating size of electrical service, or if it is a fuse system....the fuses will have current ratings. If it is a subpanel, it might not have a main breaker. In this case you would have to look in the panel that the feed is coming from and find the size of the breaker that is feeding it. In either case you must look for the manufacturer's label that will have the maximum current the panel can handle, make sure the breaker feeding the panel doesn't exceed this rating.
The breaker will have a black wire connected to it. Turn off the main breaker and then disconnect that black wire from the breaker. The breaker will snap into the main bar. Remove the breaker and install the new one. Reconnect the black wire to the breaker and then install the cover and turn the main breaker back on.
The wire is sized to the breaker in the main box that is feeding the subpanel. The calculations for the subpanel is based on what devices will use the subpanel and an estimate of duty factors for the devices. An electrician can provide this information, or you can look on-line in the National Electric Code for estimation methods.
The biggest circuit breaker in any home is the main breaker located in your main breaker panel that is installed where your electrical service cable comes into your home.
Yes. You'll seldom run every circuit to full capacity. The main breaker will trip if all the individual circuits exceed the 200 amp rating of the main breaker.
The sub-panel need to be fed from the main panel, by way of a circuit breaker connected to one of the breaker locations. Or if your sub-panel has a main breaker installed you can feed from the main panel with a sub-feed lug kit. This looks like a breaker, but is only a point where you can branch off the sub panel.
The main breaker will have marking indicating size of electrical service, or if it is a fuse system....the fuses will have current ratings. If it is a subpanel, it might not have a main breaker. In this case you would have to look in the panel that the feed is coming from and find the size of the breaker that is feeding it. In either case you must look for the manufacturer's label that will have the maximum current the panel can handle, make sure the breaker feeding the panel doesn't exceed this rating.
The main breaker limits the overall current to the building. Most buildings have many branch circuits that sum to more current than the service is rated for. This is not a problem as all the branch circuits are not used under high current draws at the same time. The main breaker protects the main wiring in the meter and to the transformer, and the transformer itself, from heavy current loads. It also protects from shorts in the main distribution panel.
Yes, it would appear that one side of the main is open at the fuse, breaker, drop conductors, or transformer.
It depends on the situation and how you are utilizing the transformer. Under certain conditions the secondary does not need to be protected. The protection on the primary is enough to protect the secondary side of the transformer.
Frist putt of the main incomer HT side then Rack out the breaker and put the LOTO after that Discharge the cable Both side (HT/LT).
The breaker will have a black wire connected to it. Turn off the main breaker and then disconnect that black wire from the breaker. The breaker will snap into the main bar. Remove the breaker and install the new one. Reconnect the black wire to the breaker and then install the cover and turn the main breaker back on.
You have to be careful with terms in the electrical field, Example: Main Feeder Circuits will feed a Transformer for distribution and each of those main circuits might feed numbeous Motor control centers. However each of those circuits could be called a main feeder for the motor control center. Confusing. We have High Voltage Transmittion tansformered down for Distribution. So normally a Feeder Breaker will feed Main circuits that will be used for distribution. Example Your home panel will have a main feeder circuit to the whole panel and distribution breakers to you home.
Nothing. If your system can run your house while the main breaker to the power grid is off, then back charging will occur as a byproduct while the main breaker to the power grid is on and you are using less power than you are generating. During times of a power outage, you'll want to cut the main breaker to the power grid, so that your system doesn't try to power the entire neighbor hood.
The usage of transformer is to produce electricity from a main electric unit
The wiring is like this:[[30KW Motor ---- Star Delt Starter(100A Breaker inside) ----- 200A Breaker------50A Breaker(Inside the breaker box which located inside the factory) -----100A Main Breaker]]Once I try to start the Motor, the Main Breaker trips immediately.
A 277/480V box should be clearly marked, but not always. The only way to be certain of a box's voltage is to use a voltmeter on it. This type of voltage is very dangerous. When voltages start to get this high, at best you may loose a finger or limb, at worst, you die. I recommend calling an electrician, who will be able to safely check this out.