Browse Prior Art Database

Primary Power Sensor

IP.com Disclosure Number: IPCOM000106896D
Original Publication Date: 1992-Jan-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 2 page(s) / 64K

Publishing Venue

IBM

Related People

Hunter, GC: AUTHOR [+2]

Abstract

A mains power-sensing device (PSD) is described to simplify control of slave system units by a master host unit. A daisy-chain modular power control can be constructed and extended to accommodate growing systems using additional PSDs of the same type/part numbers. Remote power control is provided to multiple slaves only when power is drawn from the primary supply by the host unit.

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Primary Power Sensor

       A mains power-sensing device (PSD) is described to
simplify control of slave system units by a master host unit.  A
daisy-chain modular power control can be constructed and extended to
accommodate growing systems using additional PSDs of the same
type/part numbers.  Remote power control is provided to multiple
slaves only when power is drawn from the primary supply by the host
unit.

      Advantages are that host units do not require modification in
order to use the device for remote power control;  PSDs can control
multiple slave units and are unaffected by RFI and ESD.  Costs are
low by use of orthodox electrical engineering technology.  A radially
wired network version using only one PSD is also described.

      The power sensor device 1 shown in Fig. 1 is plugged into a
host unit 2 in series with the main power cord 3. The line current
drawn by the host unit 2 is sensed by passing it through the 9-turn
primary of a small transformer (T1).  The secondary winding is
arranged to provide an output voltage in excess of 20 VAC when the
primary current exceeds 0.1 A AC.  The output voltage is converted to
DC by a full- wave bridge rectifier (BRI) and smoothed by capacitor
C1.  The DC voltage is clamped at 15 volts by Zener diode Z1.  A
bleed resistor (R1) is fitted to ensure rapid voltage decay when
primary current is reduced to below 0.1 A AC.

      When the host unit 2 is switched on, the primary current
flowing throug...