A supply constructed within a bracket with a “U” shaped profile. A protection system for supplies where the supply shuts down if temperature exceeds specified ratings. Nominal Input value(s) of either ac or dc Input voltage for which the supply is connected. The insulation strength test voltage between the input and output, and output to ground. 0000018610 00000 n See Ripple and Noise. 0000016113 00000 n The noise at an electrically fixed point (usually chassis ground) common to both dc output and return lines. The ratio (in absolute terms) of the input to the output signal is expressed in dB and listed as the input ripple rejection. Naturally, since P = E * I, power = voltage * current, you will expect than when a power … This reduces harmonics disturbance on the ac line. The temperature of still air surrounding a power supply. 50% and 100% rated load). The maximum altitude at which a supply can be operated without derating. Typical methods are convection, forced air and conduction. 48 0 obj <>stream Multiple output power supplies often require minimum loads in order for the supply to achieve stated regulation specifications. Tel: 03-6721-9396 Mean time between failures is the predicted length of time before failure of a supply, exclusive of infant mortality failures. Referring to an ac-dc power supply that inserts and mounts directly to an ac socket on the wall. 0000046441 00000 n Typically, floating outputs are fully isolated and may be referenced as either positive or negative by the user. These are system level standards, but they are also used in power supplies and dc-dc supply specifications. �n}����25�˭J�t�/��ga|M@�g`B��;���͔�hB 0000002425 00000 n The distortion characterized by the presence of multiple harmonics of the fundamental frequencies in sinusoidal ac current waveforms and caused by the switching action of the power supply typically stated as a percentage of the sinusoidal wave form, eg: 0.95 Power Factor. 0000014667 00000 n The effect on the output voltage due to varying dc load and ac input voltage. The power dissipated is the difference between the input and output power. A performance curve that describes how the efficiency varies with input voltage. A power switching circuit similar to the full bridge supply except that only two transistors are used, with the other two replaced by capacitors (see bridge converter). Periodic and Random Deviation. Also called Input Surge Current most commonly referenced in ac-dc power supplies. Switching power supplies draw input current in pulses around the peaks of the ac line voltage frequency. The instantaneous current drawn when the power supply is turned on cold. Final equipment must meet both standards while many supplies may be rated only for conducted emissions. j��_��C�K��#$e��˒*#:�Rm����1�r���p���Z�`$����a�2��AhiOh"�F��R�W�rM���R��#)��0��4�������|y;���.~|��e]���,M��/��ʢߊY�Q�e��͓�ߑ�J �=G1�x�6 U���D똉���ϰ�l��X��#M��@o�f�-M� �~��jI�7��F��tA,mǦl�f���� sT(� {�����.�7:�<1��fN]���5�K�ч��s��,^%\ǯ gq�!C��';i�!�D��m�|�gd=o3���l}���\*4�� A power supply or dc-dc supply “common” is not actually ground unless it is connected to earth. CE marking (Communaute European, European Committee) indicates that all applicable EC directives pertaining to the power supply have been met. Often referred to as margining. The allowed variance of the output voltage as set at the factory during the manufacture of a supply. Equivalent Series Resistance is a prime factor in ripple switching power devices, and it is that resistance which exactly matches the performance of a real capacitor when it is in series with an ideal capacitor. The time required, after initial turn on, for a power supply or dc-dc supply to operate within its specifications. A twisted pair of wires connected to the load in order to route output voltage back to the remote sense control circuit of the power supply. That component of noise measured with respect to output or input to its returns; it does not include common mode noise. Effective the end of the calendar year 2010, Energy Star will no longer govern External Power Supplies and their no load power consumption or efficiency levels. See also Convection Cooling. PF(power factor) is a decimal fraction between 0 and 1, and indicates the ratio of real power consumed and the RMS power consumed. Most supplies will automatically recover when temperatures return to normal. Specifically, most power supplies have a natural state of on when input is applied and may be inhibited by the remote on/off circuit. This defines the ability to replace one of multiple supplies tied in parallel. The components or circuitry drawing current from the output of a supply. It provides a reference that can be considered to have zero voltage. Typically, a cased power supply is covered on all 6 surfaces for finger safe operation. spike of current with a pulse width of less than 200μs, generated by the “X capacitors” charging up. � Q��x�J��f�9 The function of paralleling two power supplies to share a load without any active circuit to control how the load is shared. linear, switched mode flyback, half bridge etc). This minimizes the internal power dissipation under overload conditions. 0000018222 00000 n The process of removing heat generated by normal operation of a power supply. 0000043809 00000 n 0000038547 00000 n An overvoltage protection circuit which places a low resistance shunt across the power supply output terminals, if a predetermined voltage is exceeded. Traditional switched mode power supplies draw current from the ac line in short pulses, and as a result, the input current of such basic switched mode power supplies has high harmonic content. 4 45 H��W[��4~ϯУ�iTI�|���\�r����r8��lN��v��{f4�/I؇���ܿO��כ��Q�O%� ?J��W/�+�c�z�� These diodes ensure current can flow in only one direction - out of a power supply. It is most important in considering an ac switch rating. OTP usually measures the hottest spot in the supply. endstream endobj 5 0 obj <>>> endobj 6 0 obj <>/ExtGState<>/Font<>/ProcSet[/PDF/Text]/Properties<>>>/Rotate 0/TrimBox[0.0 0.0 612.0 792.0]/Type/Page>> endobj 7 0 obj <> endobj 8 0 obj <> endobj 9 0 obj <> endobj 10 0 obj <>stream This creates extra load on utility lines and increased heat of utility transformers and may cause stability problems to the entire ac Line (Especially in Europe). &�f�R���Q�-y�E�6�ջ��tb?7]�DP2#[�Wy]�u�U�G�e�J�b��c�^��0�Pf�c���q%C�@R�(Պ|\\2�!8c�lQ:ҧ#)��H��eV*C�q��$��%&�A����M��e��U�Ss�F߅R9,��}=�T�3ۅ The nominal output voltage setting of a power supply. Hermetically sealed and contained (encapsulated) in a thermally conductive epoxy resin or similar plastic. The ability to connect power supplies or dc-dc converters in parallel so that if one fails the other(s) will provide continuous power to the load. AN-21. www.cenelec.eu. This is usually achieved through independent regulation circuits for each output within the supply. This typically refers to a supply of either open-frame PCB construction or mounted on some type of bracket (L-Bracket or U-Frame) that has a cover option, These type of products are typically covered on 4 sides, leaving the ends open, though 6-sided covers are not uncommon. www.iecee.org/about/cb-scheme/. The maximum continuous output current a supply is rated for under nominal operating conditions. Typically, a twisted pair of wires is attached to the load to “sense” the voltage at the load, enabling the supply to automatically compensate for varying voltage drop. Within a specified temperature range, the maximum moisture content permissible in the surrounding air of a supply. The supply being replaced must be powered with it’s ac input removed off while the others may remain on. A protective feature that limits output power or current demands to prevent damage to the supply. 4 0 obj <> endobj When there is a loss of input power to a supply, this is the time during which the output voltage remains within regulation. The ratio of a power supply or dc-dc converter output power to its volume -typically displayed as Watts per square inch or Amps per square inch. Limit of specifications that, if exceeded, could cause the shutdown or damage to a supply. This is specified for a dc to 120 Hz input so that the effects of a full wave rectifier circuit can be evaluated. This measurement is done with a 1 kHz, 1 VRMS capacitance bridge. 0000089208 00000 n An unwanted feedback condition caused by two or more circuits sharing a common electrical line, usually a common ground line. This mode is used in systems where a single failure cannot be tolerated. See ErP for the latest in consumption and efficiency requirements. 0000043277 00000 n The change in dc output voltage of a supply over the entire input range while the output load is held constant. The combined voltage deviation a supply could experience due to any change within the specified tolerances of input voltage, output current and temperature change. This input range is typically 90–264 Vac. The independent Canadian organization (Canadian Standards Association) which tests to see that public safety regulations are met. Congress enacted the Energy Independence & Security Act (EISA) in 2007 based on the CEC limits (both are the same). The rated working voltage is typically much lower than the rated isolation voltage. The name for the return current of output voltage(s) and/or logic signals. The range over which the output voltage can be adjusted. Also called decoupling diodes. 0000010653 00000 n This technique is cost effective because a minimum number of components is required. When supplies are first turned on, a high surge input current is experienced caused by the charging of the bulk input capacitors. V L(AC line voltage) is the RMS voltage measured at the input terminals of the power supply. No additional testing by UL is required. Component (built in) power supplies and dc-dc supply products are not falling under this Directive by law. Under a short circuit condition, most supplies are designed to shut-down and typically recover to normal operation when the short is removed.

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