The abundance of power products and standards can be a designer’s nightmare. The right knowledge will help meet your global power needs.
By Rob Taylor
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Power requirements are one of the designer’s biggest challenges. When specifying power connectors and plugs, designers often find their system requires more power than they had planned. To add to the challenge, the global marketplace may require the end product to be used anywhere, from Australia to Zimbabwe. Designers must be aware of the most recent power standards and the products available.
IEC 60309 connectors are rated up to 415 VAC and 125 A for international applications, and up to 480 VAC and 100 A for North American applications. Models include single- and three-phase systems. Many IEC 60309 connectors carry VDE or SEMKO approval to EN 60309 and UL and CSA approval to bi-national standard UL 1682 and C22.2 no. 182.1. The pin and sleeve name is derived from the contact pins in the plug mating with the sleeves found in the outlet to make an electrical connection.
Most of the products that we use each day at home and at work have standard plugs for power entry. In North America, the most common plug is a National Electrical Manufacturing Association (NEMA) 5-15P, which is rated at 15A/125VAC. There are several international plug standards, such as the widely used, German-style CEE 7, used at a variety of ratings up to 16 A/250 VAC (see table, below).
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If you are designing a product for both international and North America, you should consider using the high-power pin and sleeve devices. If your product will be used domestically only, you should consider using a NEMA plug pattern (see chart, below).
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How do you provide power to your product when it draws more than the rated output of common plugs and sockets?
High-power pin and sleeve devices made to specific national standards are available, but are not good choices unless sales are limited to a few markets. Plug configurations intended for one country and being used in another country, in most cases, would not be acceptable. For example, the higher power straightblade and locking NEMA plugs used in North America cannot be used in Europe. Another example is the 32-, 40-, and 50-A Australian socket outlets used only in Australia. Note that the IEC 60309 connectors are used in Australia, but are not as common as the 32-, 40-, and 50-A Australian system.
There is another way to make high-power connections. IEC publication 60309 defines a family of connectors-including plugs, socket/outlets, and couplers for industrial purposes-that can be used on equipment for both domestic and international markets. It is no longer necessary to stock connectors for every national standard. With a minimum investment, hard wiring can be avoided.
Mobile flexibility
More and more, power-hungry equipment is smaller in size and mobile. Users can wheel equipment that was once stationary to individual work stations, or to where needed on a work site, and simply plug it in. This mobility extends the productivity of users by giving them sole control over more powerful equipment. It also increases equipment usage, thus giving your customers a greater return on investment. Flexibility such as this can give your products a competitive edge.
Some stationary equipment can also benefit from using IEC 60309 connectors. These products could be sold, in part, on the basis of how easy they are to install. In this case, specifications for the mating wall outlet and wiring instructions could be sent to the customer in advance. This wall socket might also be provided to the customer as an extra-cost accessory. The customer would then be instructed to have the outlet installed, by an electrician, prior to the equipment installation date. At that time, your product is simply plugged in and powered up. This procedure should eliminate one source of delays, distractions, and headaches for the installation team. This, in turn, should help control costs and gain higher customer satisfaction.
The IEC 60309 system was designed to ensure polarity and avoid mismating of connectors. Polarity is ensured with a polarizing key and keyway, and the diameter of the ground contact is greater than that of the other contacts. This ensures proper connection between the ground pins.
 Figure 1. International and North American operating voltaged are usually indicated by color-coded enclosures. |
Color-coded enclosures indicate the voltage ratings. Additionally, the IEC 60309 system features a series of graduated connector sizes. Each size relates to the current rating and number of contacts (see Fig. 1).
IEC 60309 connectors and socket outlets feature hinged, spring-loaded covers which snap into place when the plug is removed. This reduces the risk that foreign objects will be inserted into the contacts. The hinged cover also serves as a locking mechanism to assure that once the plug and socket are mated, they will not be accidentally uncoupled.
Models in this connector family come with seals that control the intrusion of moisture and solid objects. This is reflected in an Ingress Protection (IP) rating, which is derived from IEC 60529. The symbol for the IP rating is usually embossed on each connector.
IEC 60529 outlines an international classification system for the sealing effectiveness of enclosures of electrical equipment against the intrusion into the equipment of foreign bodies (tools, dust, fingers) and moisture. This classification system uses the letters “IP” followed by two digits. An “X” is used for one of the digits if there is only one class of protection, such as IP X4, which addresses moisture resistance only.
Decoding the code - first digit
The first digit of the IP code indicates the degree that persons are protected against contact with moving parts (other than smooth rotating shafts), and the degree that equipment is protected against solid foreign bodies intruding into an enclosure.
- No special protection
- Protection from a large part of the body such as a hand (but no protection from deliberate access); from solid objects greater than 50 mm in diameter
- Protection against fingers or other objects greater than 12.5 mm
- Protection from entry by tools, wires, etc., with a diameter or thickness greater than 2.5 mm
- Protection from entry by solid objects with a diameter or thickness greater than 1.0 mm
- Protection from the amount of dust that would interfere with the operation of the equipment
- Dust-tight
Second Digit
Second digit indicates the degree of protection of the equipment inside the enclosure against the harmful entry of various forms of moisture (such as dripping, spraying, and submersion).
- No special protection
- Protection from vertically dripping water
- Protection from vertically dripping water (15° tilted)
- Protection from sprayed water
- Protection from splashed water
- Protection from jetting water
- Protection from powerfully jetting water
- Protection against temporary immersion
- Protection against complete, continuous submersion in water
Pilot pins and contacts are included with many of the higher current-carrying IEC 60309 connectors for use in electrical interlock systems. These systems ensure power is safely disconnected before the plug and connector are disengaged. The pilot pin and contact disconnect before all other connections in the IEC 60309 and when wired to an electrical interlock, this disconnect signals the electrical interlock to shut off power.
High-power connection devices include both cable and panel-mount inlets and outlets. The need for these devices involves applications where higher voltage and amperage is needed in a protective environment. The result is a more resilient construction of the metal electrical contacts and plastic shell of the connectors.
High-power connection devices are used in applications where high-power connection needs include detachability, security, and protection. In many applications, the equipment could be wired directly to a power main through a junction box. The difficulty is that whenever equipment necessitates moving or replacement, a technician or electrician must be available to do the wiring. A detachable connection device makes this easier to move and replace highly powered equipment.
Industries that may use high-power connection devices are those that require higher amperage and voltage than found in the normal circuit of a building. These industries include, but are not exclusive to: construction, providing a power-source connection for equipment and lighting; food service, connecting heating units, cookers, fryers, and warmers, and providing power to vendor carts at fairs, shows, and booths; entertainment, providing power for lighting, sound, camera, video displays, and movement of props; and the computer industry to connect large computers, servers, and main frames.
ROB TAYLOR is the product development and quality assurance manager at Interpower, P.O. Box 115, Oskaloosa, IA 52577. Tel: (800) 662-2290; email: rtaylor@interpower.com.
