BS EN 60268-3:2013 pdf download

BS EN 60268-3:2013 pdf download.Sound system equipment Part 3: Amplifiers.
If the characteristic is to be measured for several settings of the volume control, then the position for rated conditions shall be included, other preferred settings being maximum. and —3 dB, —6 dB. —10 dB. —20 dB and —40 dB with respect to the setting for rated conditions.
Volume controls belonging to channels not being measured shall, if possible, be put in the minimum position, unless otherwise stated.
9 Pre-condltioning for measurements
Before beginning measurements on an amplifier, it shall be operated under approximately standard measuring conditions fo a period of 1 h, or as specified by the manufacturer,
Before operating the amplifier the manufacturers instructions concerning initial operation should be studied.
The amplifier is then brought under standard measuring conditions (see 3.1.3). Due to internal heating, the output voltage may subsequently vary with time. Unless excessive, this effect is ignored during the pre-conditioning period. When the pie-conditioning period is over, the amplifier shall be brought under rated conditions or standard measuring conditions, as required.
10 Series of measurements
If a series of measurements is made, the amplifier should preferably be maintained under standard measuring conditions In the periods between measurements.
If the amplifier has to be put out of operation for an extended period between measurements, then pre-conditioning according to Clause 9 shall be repeated before each set of measurements, unless this can be shown to be unnecessary.
11 Variable consumption apparatus
Sound system equipment shall be considered as variable consumption apparatus if it contains one or more power amplifiers operating in the Class AB. B, or D modes, in which the d.c. power supply for the output stages is either electronically regulated by means of series control elements or is not regulated
NOTE 1 Variabli Consumption apparatus is d.fin.d In iEC 60065:19762 as ‘apparatus in which th, power consumption can vary more than 15 % due to changes in load Impedances of the output Civcuit Ot in Signal parameters’, but no deñnltion appears In the fIfth (1985) or sastn (1998) editIons
NOTE 2 Where the dc. supply Is regulated by shunt oontrol elements, the power consumption 11 usually, it not aiways, subsianticily constant Th. apparatus. how.v.r. b.hev.s in some respects as a vaneble consumption apparatus, and, In parircular, the text o 147.4.1 tIt applies.
All the measurements contained in this standard may be performed on variable consumption apparatus, in most cases with no special problems. However, certain problems may occur in the measurement of hum and rated distortion-limited output power, and some additional measurements are valuable In assessing the performance of such apparatus (see the note of 14.6.3.1 and item c) of 14.14.3).
12 Marking
Principles for marking the terminals and controls are given in IEC 60268-1.
— personal safety and prevention of spread of fire, in the sense of IEC 60065;
— safety In case of faulty connections;
— indications relating to normal operation, according to IEC 60417.
Marking can neither prevent incorrect operation nor provide complete operating instructions. It therefore has to be considered in conjunction with adequate means for preventing dangerous or faulty operation, and with the directions for use included in the user’s instructions, Care should be taken that marking is unambiguous and as clearly understandable as possible.
Terminals for the interconnection of equipment, which are inaccessible without the use of a tool when the equipment has been installed, shall be clearly and unambiguously identified with respect to the manufacturer’s instructions for installation, It may be assumed that these in5tructions are to be read by adequately skilled personnel.
13 Operating environment
Measurements, especially those including temperature measurements, shall be carried out with the amplifier mounted in a situation similar to that in which it is to be used. Restrictions on mounting and special ventilation requirements shall be stated by the manufacturer and form part of the rated conditions (see 3.1.2). See also IEC 60065 or other appropriate IEC safety standard.
14 Characteristics to be specified, and their methods of measurement
14.1 Power supply characteristics
14.1.1 Characteristics to be specified
The following information shall (except where indicated as optional) be stated by the manufacturer in the locations indicated, for each pair of terminals to be connected to the power supply and for each position of the power supply voltage selector, if any:
a) the type of power supply (d.c. or ac.); on the equipment and in the specification;
b) the rated power supply voltage (this is a rated condition, see 3.1.2): on the equipment and in the specification
c) the power supply frequency or range of frequencies (this may be a rated condition, see 3.1.2): on the equipment and in the specification.