Power connectors are female power connectors into which plugs or male connectors are inserted to make circuit connections. They transfer alternating current (AC) or direct current (DC) through a variety of electronic devices.

Types of Power Connectors

Several types of power connectors are available.

Plug/inlet- Plugs are male connectors which consist of the socket contacts. They connect to electrical receptacles, wall outlets, or sockets and draw current from these female connectors.

Receptacles/ outlets are also called jacks. They are the female or receiving connectors which mate to the male (plug) connectors.

Power entry modules serve as switches, fuses, or filters. Others serve as circuit breakers or indicator lights. They mount on the case or panel of a machine and attach to the power cord.

Specifications

Important specifications for power connectors include:

Power connectors provide maximum voltage and maximum current ratings. Typically, devices are designed for either single-phase or three-phase power. Maximum voltage ratings include 125, 250, 277, 347, 480, and 600 V. There are two maximum voltage ratings for 4-pole, 4-wire and 4-pole, 5-wire devices: 120/208 V and 277/480V. Voltage ratings for 3-pole, 4-wire electrical devices include 125/250 V. Voltage ratings for 4-pole, 5-wire devices include 347/600 V. Power connectors provide a variety of maximum current ratings, including 15, 20, 30, 50, 60, and 100 A. International current ratings include 16, 32, and 125 A.

Number of poles- Poles control one path of the circuit. A pole is an outlet terminal for a switching device, a combination of mating contacts, or both. Typically, power connectors have between one and five poles.

Grounding

Grounding is the term used to describe a safe path for electricity to move from a defective outlet, fixture, appliance or tool back into the earth, which is a very good electrical conductor. There are different grounding options available based on the needs of the system. These include,

Non-grounding connectors do not have a ground option.

Standard grounding devices have a standard embedded ground terminal

Isolated grounding devices use a ground path that is isolated from the facility's grounding systems. This increases the resistance of sensitive electronics to surges. They also provide a clear grounding path to the service panel and help reduce electromagnetic noise that can interfere with equipment operation.

Self-grounding connectors establish a connection to en existing grounding path such as a metal wiring device or metal conduit, gas or water pipe, or ducting or structural steel.

Ground fault circuit interrupter (GFCI) connectors include a built-in circuit that detects leakage current to ground on the load side of the device. When leakage current is detected, GFCI interrupts power and prevents hazardous ground fault conditions. National Electric Code NFPA-70 requires GFCI use in many indoor and outdoor locations.

Mounting

There are several mounting styles for power connectors.

Standard DIN rail or fit the ends of electrical cables.

Panel mounted devices fit a depression within a panel so that they are flush or nearly flush with the surface.

Flange mounted devices attach by bolting the flange or riveting it in place through holes in the flange surface.

Wall or box mounted electrical receptacles include an accessory such as a back shell for permanent mountings.

Through hole technology (THT) mounts electrical receptacles on a printed circuit board (PCB) by inserting component leads through holes in the board and then soldering the leads in place on the opposite side of the board. 

Surface mount technology(SMT) adds components to a printed circuit board (PCB) by soldering component leads or terminals to the top surface of the board. Typically, the PCB pad is coated with a paste-like formulation of solder and flux. With careful placement, SMT components on solder paste remain in position until elevated temperatures, usually from an infrared oven, melt the paste and solder the component leads to the PCB pads.

Terminals

Terminals are devices that terminate a conductor. They attach to posts, studs, or other conductors in order to establish an electrical connection. There are several options including,

• Cage clamp- Electrical connections are made using a cage clamp.
• Crimp- Crimp is the physical compression (deformation) of a contact wire barrel around a conductor to make an electrical and mechanical connection to the conductor.
• Insulation displacement connectors (ICD)- slice through cable insulation to make a connection. Forcing an insulated conductor into a restrictive slot in the connection part of the contact displaces the insulation so that the bare wire engages the sides of the slot. IDCs are mass termination connectors for flat cables and eliminate the need to strip insulation.
• PCB solder- Electrical connection is made by soldering wires onto a printed circuit board (PCB).
• Screw- Electrical connections are made using screws.
• Lugs- Electrical connections are made using lugs.
• Solder cup or solder- Solder cups are terminal ends or contacts into which conductors are inserted before soldering. A metal or metallic alloy is used to join metal surfaces together. Normally, a 60-40 rosin core (60% tin and 40% lead) is used for soldering electronic assemblies. Soldering is a wet process.
• Tabs- Electrical connections are made through quick connect tabs.
• Wire wrap- Electrical connections are made by wrapping a stripped or unstripped solid wire around a terminal post that contains a series of sharp edges. This solderless process requires a special wrapping tool.

Features

Power plugs have several features available that may be beneficial for user application.

Corrosion resistant- Corrosion resistant devices are made of special materials and/or plated metal parts that are designed to withstand corrosive environments. Corrosion resistant devices must pass the ASTM B117-13 five-hundred hours Salt Spray (Fog) Test with no visible corrosion.

Dust proof- Devices are designed so that dust will not interfere with their operation. The IP suitability rating describes the degree of protection that a device offers against the ingress of foreign objects (e.g., IP 20).

Power light- Devices include a power light to indicate if they are live. The receptacle may also be illuminated to make connection easier in dim or dark work spaces.

Tamper resistant- Devices are constructed so that access to their energized contacts is limited. Tamper resistant receptacles are required by the National Electric Code NFPA-70 in specific pediatric care areas in health care facilities.

Watertight- Devices are constructed so that water cannot enter under specified test conditions. The IP Suitability Rating designates the degree of protection a device offers against the ingress of moisture and water (e.g., IP-55, IP-44). Some devices may also be approved for moisture resistant, and under water applications.

Quick connect / disconnect- Connectors incorporate a quick-connect mating geometry, typically by twisting and seating for positive contact. They can be disconnected quickly and then easily connected to another machine or device.

Integral features are built into the design of the power plug.

• Fuse protection- Devices include integral fuse protection against mild to moderate spikes or peaks in electrical supply. The fuse will blow before connector is damaged.
• Integral surge protection- Devices include integral surge protection against mild to moderate spikes or peaks in electrical supply.
• Integral circuit breaker- Devices include an integrated circuit breaker that will "trip", severing the connection to the electrical supply, in the event of an excessive power transfer.
• Integral switch- Devices are equipped with an integral switch. Toggling the switch to the "off" position stops the electrical power transfer through the connector.
• Integrated filter- Devices provide protection against unwanted signals or magnetics and may provide signal conditioning or isolation. Typically, filters are designed to reduce electromagnetic interference (EMI) and radio frequency (RFI).

Applications

Specialized power plugs are used for specific types of instruments, equipment, machinery, and computers. Some electrical connectors are designed for use in hazardous environments or marine environments. Power plugs are used in almost every industry including residential, commercial, industrial, and medical facilities.

Standards

Power connectors are designed to meet requirements from the following organizations:

• National Electrical Manufacturers Association (NEMA) - NEMA sets standards for electrical cabling and connectors.
• Institute of Electrical and Electronic Engineers (IEEE) - IEEE is a worldwide organization who develops standards in many areas related to electrical and electronics.
• The International Electrotechnical Commission (IEC) - IEC is a worldwide body responsible for developing consensus global standards in the electrotechnical field.
• Consortium for Energy Efficiency (CEE) - CEE is a European organization for electrical standards.
• Japanese Industrial Standards (JIS) - JIS is a Japanese organization for electrical standards.

There are many organizations across the world that determine and maintain electrical standards to ensure safe and efficient use of power plugs. Engineering360 allows users to search by country to ensure they select a power connector that can be safely incorporated into their system.

Resources

Power Connector Tutorial

Electrical Current Worldwide