(2 PCS) P1467 BEST WINDINGS LOW PROFILE LINE HOLD CHOKE

Description: P1467 is a choke designed for application to standard 600Ω PSTN line terminations in cases where the height available is limited, it has a split winding in order to permit balanced-mode signalling. It is intended for use with line transformer P1200 and has a low maximum seated height of only 14.6mm. Other transformers may be used but they may require different component values. The P1467 is designed with BS 6301 para. 4.4 in mind, which specifies certain overvoltage tests, and is therefore constructed using materials having adequate margins. Under conditions of very poor ventilation the overvoltage test causes a winding temperature rise of 137ºC. As well as this, balanced mode signalling carries risk of short-circuits from line to ground; protective measures may be needed to deal with this situation. Under normal worst-case conditions the rise is 100ºC after 2 hours continuous line hold.Choke P1467 can easily be arranged to meet BS 6305 Class (a). In view of this there is no point in considering Class (b) further in these notes, although Class (b) can be met with a wide safety margin except for the restriction on modem line terminal impedance. P1467 is ideal in situations where lightning strikes make semiconductors vulnerable.