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Ringer equivalence number/ v$ g+ P5 v9 r. B/ E; N
http://en.wikipedia.org/wiki/Ringer_equivalence_number
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In telecommunication, a ringer equivalence number (REN) is a somewhat arbitrary number which denotes the electrical load a telephone ringer has on the line. In the U.S., this is determined in accordance with ANSI/TIA-968-B (August 2009).
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REN is a United States-developed yardstick, but analogous systems exist internationally. In some countries, (particularly in Commonwealth nations), the REN is better known as the ringer approximated loading number (RAL).- X# @+ d1 f, z" j( J" O
& V, ^/ s' B- t. `8 L& O; PIn the United Kingdom it is called the ringer equivalence number and a maximum of 4 is allowed on any British Telecom (BT) line.& B. i' @& a7 A$ o
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In Canada it is called a Load Number (LN); which cannot exceed 100. (The LN of each device represents the percentage of total load allowed).
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! R2 A5 o) b6 J& J4 {5 LIn the United States 1 REN was formerly equivalent to a 6930Ω resistor in series with an 8 µF (microfarad) capacitor. The modern ANSI/TIA-968-B specification (August 2009) defines 1 REN as an impedance of 7000Ω at 20Hz (type A), or 8000Ω from 15Hz to 68Hz (type B).5 b5 s% P& `/ a/ t
7 Z2 w$ q7 h- {( M. Z8 RIn Europe 1 REN used to be equivalent to an 1800Ω resistor in series with a 1 µF capacitor. The latest ETSI specification (2003-09) calls for 1 REN to be greater than 16 kΩ at 25 Hz and 50 Hz. |
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