Basics in low voltage distribution equipment - Eaton

1 Thought leadership White paper Basics in low voltage distribution equipment Mark Rumpel Basics of electricity generation Product line manager Eaton In the , as elsewhere, electricity has historically been generated from precious natural resources including coal, oil or natural gas. Nuclear energy and hydropower innovations advanced electrical Executive summary generation capabilities at the end of the 20th century. Today, Depending on their unique needs, multi-family, commercial and alternative and renewable fuels such as geothermal energy, wind industrial sites typically rely upon either low or medium voltage power, biomass and solar energy are gradually becoming more service entrance equipment to control or cut off the electrical readily available; these sources are popular both for their higher supply of their buildings from a single point.

2 Low voltage efficiency and long-term sustainability. distribution equipment typically operates at less than 600 volts; Once harvested, natural resources and mechanical energy sources in contrast, medium voltage equipment affords a wider range must first be converted into electrical energy to make it transmis- of 600 to 38,000 volts. sible and usable. Power plants complete this function using steam This paper provides a basic overview of the definitions, turbines. components, applications and other details associated Water is heated in a massive boiler to produce steam, which is used with low voltage distribution equipment .

3 It covers electrical to turn a series of blades mounted on a shaft turbine. The force of panelboards, switchboards and switchgear operating at the steam rotates a shaft connected to a generator. The spinning 600 volts alternating current (AC) or direct current (DC) or below. turbine shafts turn electromagnets surrounded by heavy coils of The information is intended to help readers understand the copper wire inside generators. This creates a magnetic field, which purpose of electrical distribution systems and associated causes the electrons in the copper wire to move from atom to atom, equipment and increase their technical knowledge about it.

4 Thereby creating electricity. After the turbines have generated electricity, voltage must be increased to transport it as power. This is accomplished by passing the electricity through a series of step-up transformers for routing onto a network of high voltage transmission lines. Electrical power then travels very efficiently and safely over long distances along these lines. voltage is stepped up voltage is stepped back by transformers down by transformers Electric utility provides Transmission lines move electricity Electricity is used generated electricity closer to utilization points Figure 1.

5 Understanding energy production and electrical distribution : from generation to transmission to consumption. Electrical distribution systems further facilitate the economic and More commonly referred to as the box or can, the enclosure safe delivery of adequate electrical power to all the electrical provides the housing in which all the other panelboard components equipment used in a home, commercial building, or industrial reside. Enclosures are made of galvanized or painted steel to provide facility. The transmitted power arrives first at an electric distribution protection for personnel and internal equipment .

6 Removable end substation, where it is passed through a series of step-down panels allow for simple conduit installation where installers can transformers that again lower the voltage to more usable levels. easily locate and cut holes as needed. Finally, the usable electricity enters the building at a single point Inside the enclosure, overcurrent protection devices, busbars known as the service entrance. Power enters through a main and other components are mounted on support rails. This interior device (circuit breaker or fusible switch) located within an electrical assembly is commonly called a chassis.

7 Circuit breakers are assembly referred to as the service entrance electrical distribution commonly used as circuit protection devices and are connected equipment . to the busbars by bus connector fingers. Panelboards, switchboards and switchgear can all be used as service A busbar is a conductor used as a connection point for multiple entrance electrical distribution equipment or at a point downstream, circuits. Busbars are mounted to insulators on the interior rails, in which case it is known simply as power distribution equipment . which are then mounted to studs inside the box.

8 A neutral bar is Each option offers unique uses and benefits to the multi-tenant also chassis- or gutter-mounted next to the interior, providing the home, commercial facility or industrial site, so it is helpful to termination point for the neutral wires from the incoming service consider each in greater detail. and the load circuits. Panelboards should always be well labeled. Labels provide Panelboards regarding the unit's voltage rating, ampacity, interrupting rating, A panelboard is a component of an electrical distribution system that manufacturing date, panel vintage and renewal parts.

9 This information divides an electrical power feed into branch circuits while providing is critical to ensuring the safety of people and equipment . a protective fuse or circuit breaker for each circuit in a common Enclosures feature a front cover piece known as the panelboard's enclosure. In essence, panelboards are used to protect against deadfront and trim. This component covers the front surface of the electrical overloads and short circuits while distributing electricity panelboard and provides a hinged access door that allows access throughout a building or facility.

10 To the circuit breakers while preventing contact with the energized The main components of a panelboard typically include the interior components. Filler plates cover any unused pole spaces not enclosure, interior, circuit protection devices, labels, deadfront occupied by a circuit breaker. and trim, and filler plates. The National Electrical Manufacturers Association (NEMA ) has established guidelines for electrical equipment enclosures. A NEMA. Type 1 enclosure is the standard for indoor panelboard enclosures. Panelboards can be installed using one of two common approaches.