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Alternating Current (abbr. AC)
An electric current that reverses direction in a circuit at regular intervals.
British Standards (abbr. BS)
British Standards is the National Standards Body of the UK responsible for facilitating, drafting, publishing and marketing standards and related information. British Standards provides organizations with leading-edge best practice solutions that represent and support the needs of UK business and society at home and abroad.
British thermal unit (abbr. Btu)
a unit of heat required to raise one pound of water one degree Fahrenheit at one atmosphere pressure; equivalent to 251.997 calories.
Direct Current (abbr. DC)
Electric current which flows in one direction only through a circuit. The associated direct voltages, in contrast to alternating voltages (Abbr. AC) , are unchanging in their polarity.
AC to DC multiply AC voltage by 1.41 and current by 1.7
DC volts to AC volts DCV x .71
Frequency
Supply Frequency
The mains frequency in the ECC is 50 hertz and in the USA 60 hertz. (see Hertz)
Hertz (abbr. Hz)
Frequency is measured in Hertz (Hz), which is the same as ‘oscillations per second’ or ‘cycles per second. The mains frequency in the ECC is 50Hz and in the USA 60Hz all our transformers are designed for 50/60Hz. We can design for higher frequency up to 400Hz (this will make the transformer smaller).
With higher frequency transformers wire remains unchanged but core and turns may be significantly smaller (150Hz will be one third the size and number of turns of a 50/60Hz transformer)
Horsepower (abbr. hp)
A unit of power in the U.S. Customary System, equal to 745.7 watts or 33,000 foot-pounds per minute.
Inrush current
Inrush current or input surge current refers to the maximum, instantaneous input current drawn by an electrical device when first switched on.
Generally, toroidal transformers have a higher switch on surge current which could trip a miniature circuit breaker (MCB), in normal operation.
Type 4 or motor rated MCB’s should be used in such situations.
Inrush current could be more than 50amp for a few micro seconds.
A surge limiter could be provided these are about a £1 each
Kilohertz (abbr. kHz)
Kilohertz is a measurement of AC frequency equal to 1,000 hertz.
Kilowatt (abbr. kW)
unit of measure equal to 1000 Watts.
Radio-frequency interference (abbr. RFI)
Interference from sources of energy outside a system or systems, as contrasted to electromagnetic interference generated inside systems.
Regulation
This is the power lost (heat) in the normal operation of the transformer. A regulation of 6% means the transformer is 94% efficient.
Toroidal
Shaped like a donut.
Turns per volt (abbr. TPV)
The number of turns required giving one volt.
Turns / volts = TVP
VDC
(see Volts of continuous current)
Volt-ampere (abbr. VA)
A unit of electric power equal to the product of one volt and one ampere, equivalent to one Watt.
Volts of continuous current (abbr. VDC)
Volts (V) of continuous current (direct current (DC))
Watts (abbr. W)
An International System unit of power equal to one joule per second.
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