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Too hard to tell you what to do without knowing more about the power system both on the primary and secondary side of the transformer. Find a good reference on doing this using per unit quantities. A good method recommended by ANSI involves creating separate R and X networks to simplify the complex impedance calculation. You should also take into account motor contribution if appropriate.

The secondary side short circuit current for a 3 phase transformer = Volt amp transformer rat ...

Service Factor (SF) is a concept unique to NEMA design motors and is defined as a percentage by which the motor can withstand an increased load while still maintaining rated torque and speed within an accepted tolerance, even though current is expected to rise.

This should be a short time rating. You will never find an amount of time discussed, mostly because it is unclear and vague. When using a motor's service factor, an increased temperature rise is to be expected and therefore ...

In static excitation system, at starting we can use DC supply or station supply (field flashing). This system has fast response which is essential requirement now. The basic difference between static and brushless excitation is in static system all components are solid state, no moving parts while in brushless system components (diode rectifier) are rotating. Brushless has a merit that there is no brush and slip ring required as in case of static system which led to maintenance problem.
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The most basic difference is the power source. AC motors are powered from alternating current (AC) while DC motors are powered from direct current (DC), such as batteries, DC power supplies or an AC-to-DC power converter. DC wound field motors are constructed with brushes and a commutator, which add to the maintenance, limit the speed and usually reduce the life expectancy of brushed DC motors. AC induction motors do not use brushes; they are very rugged and have long life expectancies. The f ...

This is my 39th year working for or calling on electric utilities. I have not seen any ulterior motives. Many of my utilities have electively chosen not to add smart meters due to cost, and due to competition.

The excitement of smart grid, seems to be driven more by media and the "sexiness" of the idea that everything from generation of all kinds to loads in a home can be matched w/o human intervention. Practically speaking utility engineers have been "automating for decades, cons ...

Generators can have up to three power output ratings: standby, continuous, and prime. Standby is the least conservative rating, the most power the generator can deliver. The prime is the most conservative. The prime rating of a generator is used where utility power is considered unreliable or not available. Manufacturers have technical papers defining how the ratings are determined and what they mean. Different manufacturers may have slightly different definitions.

Caution, the te ...

Sometimes adding more ground rods and pipes will not do achieve anything to bring the ground resistance down in high resistivity areas. Especially sometimes, adding more ground rods will not do anything to bring the resistance down (the resistance stays the same).

A good understanding of soil resistivity and related testing is extremely important. Some guidelines should be established for the soil testing. Similarly the testing and spacing to determine the soil resistivity with de ...

While the applied cost of Solar PV has been steadily dropping thanks at least in part to the Investment Tax Credit (ITC), it remains to be proven if its intended effect will be realized. Will the ITC have stimulated enough commerce to create market demand (supported by sufficient research, development, manufacturing, marketing, distribution, contractor understanding, competition, and end-user desire) to sustain growth beyond 2016? I certainly hope so.

But, even if it has - it will ...

In its simplest form an induction generator is simply an induction motor that is rotated above synchronous speed. Unlike a synchronous generator, the field in the rotor is created by drawing large amounts of reactive current from the line.

Synchronization is automatic because line frequency is applied to the stator once the prime mover has accelerated the rotor to near synchronous speed. Remember, unlike a synchronous generator, there is no rotating field on the rotor until it is ...

Gears are used for transmitting power from one part of a machine to another. In a bicycle, for example, it's gears that take power from the pedals to the back wheel. Similarly, in a car, gears transmit power from the crankshaft (the rotating axle that takes power from the engine) to the drive shaft running under the car that ultimately powers the wheels. You can have any number of gears connected together and they can be in different shapes and sizes. Each time you pass power from one gear wh ...

Passive filters consisting of a bank of tuned filters and/or a high-pass filter have been broadly used to suppress harmonics because of low initial costs and high efficiency. However, passive filters have the following drawbacks:
1) Filtering characteristics are strongly affected by the source impedance
2) Amplification of currents on the source side at specific frequencies can appear due to the parallel resonance between the source and the passive filter
3) Excessive harmon ...

Most of the static duel conversion UPS systems operate the same. Rectifier produces a regulated output subject to its designed limits, and input source. But its output is subject to the requirements of its loading, which is the inverter and batteries. Typically the rectifier is rated at 125% of the system load. Designed to provide 100% load and 25% recharge for the batteries. Enabling battery recharge around 10 minutes for every 1 minute of discharge.

The inverters are designed to ...

Transformer sizing is a common detailed subject and it's having different conditions / philosophy based the different type of the transformer to be sized. Generator step up transformer of an ac power plant is having different concept from that is applicable for distribution transformer. Station or startup transformer is having it's own philosophy to size the optimum rating. In general, the distribution transformers are widely sized and the parameters to be considered as following points:

Let us consider an inverter based distributed generation unit.
There can be many pros and cons
Pros:
1) Can be used in the micro-grid mode when the grid is out or due to an intentional Islanding.
2) Better voltage regulation depending on the controllers applied.
3) Better frequency regulation.
4) Provide grid support
5) Line loss reduction.

But, if we employ static generators at distribution levels, we have to know that the system stabilit ...

In single phase motors capacitor is used to convert motor to two phase. Otherwise the single phase motor will not have starting torque. Capacitor is connected in series with the starting winding of the motor. The value of the capacitor depends on the starting torque required. Phase advancement in the starting winding with respect to running winding is the key. There is nothing called as 3 phase capacitor or single phase capacitor. Capacitors are individual components and have only two termina ...

We have a 2 by 275kW wind power generators connected to a system with two generators one giving a maximum of 500kW and the other 180kW both having speeds of 750 rpm. All these are to supply a load of about 470kW normal hour and a peak load of about 650kW. The problem is one diesel generator (500kW in this case) is not able to be supply load when interconnected with the wind turbines due high frequency swings (47Hz to 53Hz and the diesel gen-set finally falling off) to reduce this effect we ar ...

Transient recovery voltage generally occurs because of current chopping phenomena before natural current zero. In case of low current there may be a chance of current Chopping i.e. ARC INTERRUPTION before natural current zero, so whatever the stored magnetic energy i.e. 1/2 Li^2 present in the circuit is converted in to electrostatic energy i.e. 1/2 CV^2. So generated transient recovery voltage = (L/C)^1/2 X i

Now because of transient recovery voltage dielectric strength of dielect ...

The voltage levels, particularly at the high-voltage and extra-high-voltage levels, have long been standardized in different industrialized countries. The North-American system is 60 Hz, while the European system is 50 Hz. Each other country in the world (as far as I know) follows one or the other frequency standard. Japan is the only country I know of that has both 50 Hz and 60 Hz systems.

Then, once you've picked your "syste ...

There is an ANSI/IEEE standard that defines the standard number identification for electrical devices. You will find that some of the more common ones are 50 over current, 51 short term over current, 27 under voltage, 59 over voltage, and 50G ground over current detection relay.

Older installations may have the older electro-mechanical relays. Most installations have converted to using sensing devices that transmit to PLC, DCS or protective relays. Today's protective relays are es ...

No device has an infinitely fast response to an input, so the rise and fall times are specified for each one. As the variable frequency drive signals increase in frequency and shorten in duration, more time proportionately is spent "in transition" rather than at one or the other power rails. While the device is in transition, it will need to dissipate additional energy as heat, and raise the operating temperature locally.

Pretty much all semi ...