Dakota Transformer
Distribution, single phase, three phase, or pad mounted transformer, to rebuild, recondition, refurbish call Dakota Transformer is the place to go.
An electrical component used to transfer electric energy from one alternating current (AC) circuit to another by magnetic coupling. Essentially it consists of two or more multiturn coils of insulated conducting material, so arranged that any magnetic flux linking one coil will link the others also. The mutual magnetic field acts to transfer energy from one input coil or primary winding to the other coils, which are called secondary windings.
Distribution Transformer Standards and Purpose
These standards are published by the American National Standards Institute (ANSI). ANSI Standard C57.12.20 covers "Requirements for Overhead-type Distribution Transformers, 67,000 Volts and Below; 500 kVA and smaller." They also have requirements for pad mounted and other different types of transformers. The purpose of a transformer is to reduce the primary voltage of the electric distribution system to the utilization voltage serving the customer. A transformer is a static device constructed with two or more windings used to transfer alternating-current electric power by electromagnetic induction from one circuit to another at the same frequency but with different values of voltage and current.
The capacity of a transformer is determined by the amount of current it can carry continuously at a rated voltage without exceeding the design temperature. The transformers are rated in kilovolt-amperes (kVA), the capacity is limited by the load current which is proportional to the kVA.
When a transformer is removed from service as a result of an automatic operation of the protective devices, the transformer should be tested to be sure it does not have an internal fault before it is reenergize by a lineman. An internal weak-link fuse may exceed the available fault current from the electric system and fail to prevent the explosion of the transformer because permitting internal arcing under oil in the transformer. Linemen have been injured or killed by the explosion and oil fire that resulted.
Distribution Transformers and Power Plants
Transformers receive their electricity from the power plant, through a primary
line in the form of AC power. This current passes through the primary winding and causes a magnetizing current to flow in the secondary winding. As the wire cuts the magnetic field, it causes a current to flow. Once the field stops moving across the wire the current stops, but since our power is alternating it is always moving across the wire and causing a current in the secondary winding. The windings are wrapped because it causes a greater magnetic field and makes the transformer more efficient and compact. The voltages induced in each turn of the primary and secondary winding coils will be approximately equal, and the voltage induced in each winding will be equal to the voltage per turn multiplied by the number of turns.
Vp(primary) = Vt(volts per turn) x Np(# of turn in primary winding)
When we know the source voltage (primary voltage) and the number of turns in the primary and secondary windings, we can calculate the secondary voltage. For example, if a transformer has a primary winding with 15240 turns and a secondary winding of 120 turns and the source voltage equals 15240 volts, the secondary voltage equals 120 volts.
Transformers contain a core and coils which are composed of the primary and secondary windings, that have been wound on a laminated steel core, a primary fuse mounted on the bottom of the primary bushing, a secondary terminal block and a low-voltage circuit breaker.
Transformers are now being manufactured with amorphous mettle cores. The amorphous mettle reduces the core loss in a transformer and increase the transformers efficiency. The core loss has beem shown to be reduced more than sixty percent over the earlier laminated mettle system.
Core loss, come from two places: eddy currents and hysteresis. Eddy currents are when the magnetic fields pass through the windings they also pass through the core this induces electrical currents in it because it is a conductor as well. Hysteresis, occur when the magnetic field changes it causes the atoms in the iron core to realign, because they have a positive and a negative pole. Every time the field changes it causes a new realignment, which takes energy.
Distribution Transformer Types
Single phase transformers have same amount of time below the zero magnetic influence line as it does above it. While three phase power has three wires moving across the magnetic field in the generator that are spaced evenly apart by 120 degrees. This allows power to flow through the wire and transformers more efficiently. Allowing up to 73 percent more power transmitted though a power line.
This single mounted transformer is equipped with a surge arrestor, a
low-voltage circuit breaker, and an overload warning light. A partial-range
current-limiting fuse is mounted on the primary bushing, connected to the
primary winding to prevent a violent failure of the transformer if an internal
fault develops. This type of installation is typical for 5kVA to 50 kVA transformers.
These triple mounted transformers are equipped with surge arrestors and partial-range current-limiting fuses. The transformers are also typically are self-protected with an internal weak-link fuse in series with each of the primary windings and a secondary circuit breaker in series with each of
the secondary windings. These transformers provide 120-volt three-phase service for the customer. This type of installation is typical for 25kVA to 50kVA transformers.
Typical three-phase pad mounted transformers are primarily used for commercial installations. The transformer reduces voltage to 240/120 volts. The primary and secondary terminals of the transformer are connected to underground cables.
If you need a transformer, single phase, three phase pad mounted or refurbished Dakota Transformer is the place to go.
Dakota Transformer
1000 W. Elm Ave.
Flandreau, SD 57028
Toll Free: (800) 554- 4264
Phone: (605) 997-3971
Fax: (605) 997-2491
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