Power entry module
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A power entry module is an electromechanical component used in electrical appliances and electronic equipment, replacing a power inlet connector and one or more other components. They can be helpful in saving space and cutting manufacturing costs.
Power entry modules (sometimes abbreviated to PEMs, see [1] are used to save labor in manufacturing electrical and electronic equipment powered by an external source, such as the AC powerline. They are also quite compact, taking up a small amount of space on the equipment’s chassis, or printed circuit board.
AC power entry modules usually include IEC 60320 AC appliance inlets and accept power cord connectors designed to the same standard due to their wide acceptance. (These household devices and portable equipment are covered by IEC 60950.) Other components commonly found in power entry modules include line switches, fuse holders, circuit breakers, EMI/RFI line filters (designed to IEC 60939) and shields and IEC 60320 power outlets. As many as four or more components can be integrated into a power entry module.
They are designed to save labor, and frequently allow connections to the equipment circuitry using quick connect tab terminals. The AC inlet connector allows use of a separate, detachable AC line cord that has the type of wall plug favored by the locality. IEC 60320 AC inlet connectors can handle either 120 or 250 volts.
Since most power entry modules connect to the AC powerline, they are subject to safety standards set by Underwriters Laboratories (UL), the Canadian Standards Association (CSA), Verband der Elektrotechnik, Elektronik und Informationstechnik (VDE), and many other safety standards agencies such as BSI. Power entry module manufacturers take on the responsibility of producing power entry module products in such a way that they meet the standards of one or more of these safety standard agencies, so equipment manufacturers using them needn’t worry about safety issues. They also pay testing labs to test their products against the safety standards, so the products can carry the agency’s approval mark. AC Power entry modules often have dielectric strengths of 2000 volts or more, and can handle currents of up to 10 to 20 amperes at 250 volts maximum. Exceeding these ratings can cause unsafe operation and must be avoided.
Medical devices can and do take advantage of power entry modules. Power entry modules are available with EMI/RFI filters with very low leakage current ratings, even those suitable for direct patient contact in accordance with UL 544 and IEC 60601-1. Shock-safe fuseholders have also been integrated into power entry modules. These devices require a tool to remove the fuse for replacement.
DC power entry modules have been less common, but are finding popularity with equipment manufacturers, especially those that supply equipment in both AC- and DC-powered versions. The DC-powered versions of such equipment are frequently used in telecom central office applications.
Newer units are also available rated water resistant at IP65 with seal protection at the panel opening, around the fuse holders when provided, and between the inlet housing and connector pins.
[edit] References
Technical Article: What are Power Entry Modules? [2]
