 Program reviewing device in numerical control processing apparatus |
| It is an object of the present invention to provide a program reviewing device in a numerical ... |
|
| Numerical control apparatus for a machine tool |
| In view of the foregoing, it is an object of the present invention to provide a NC apparatus for ... |
|
| Electric discharge machine including means for detecting abnormal discharge conditions |
| An object of the present invention is to provide, in light of the aforementioned problems, an ... |
|
| Jump control system for an electric discharge machine |
| I claim: 1. A jump control system for an electric discharge machine having a discharge state, ... |
|
| Process and apparatus for electric discharge position detection |
| The present invention seeks to provide a technique for detecting the position of generated electric ... |
|
| Frequency response equalizing network for an electrostatic loudspeaker |
| OF THE INVENTION FIG. 1a illustrates quite schematically an electrostatic loudspeaker system ... |
|
| Method of effecting communications using common cryptokey |
| It is therefore an object of the present invention to provide a method of effecting cryptographic ... |
|
| Fastening straps and articles employing fastening straps |
| To achieve these objects, the invention provides a fastener comprising an elongated flat connecting ... |
|
| Automatic tone control for stringed musical instruments |
| OF THE PREFERRED EMBODIMENTS With reference to the Drawing, and initially to FIG. 1, an automatic ... |
|
|
Apparatus for sensing current transformer primary current as a function of differential core inductance
| Details |
Inventors: Tompkins, Russell E.; Walden, John P.; Walker, Loren H.;
Assignee: General Electric Company (New York, NY)
Primary Examiner: Moore; David K.
Assistant Examiner:
Attorney, Agent or Firm: Cahill; Robert A., Bernkopf; Walter C., Schlamp; Philip L.
The secondary winding of a current transformer is driven by a high frequency AC source to excite the core to alternating, uniformly equal positive and negative peaks of current excitation. An inductance sensor alternately senses the secondary winding inductances at corresponding points adjacent the positive and negative peaks of the flux wave generated in the core. Any difference in these inductances is a function of low frequency primary current and is utilized to develop a current flowing through a tertiary core winding to equalize these inductances. This tertiary winding current thus becomes a precise measure of the primary current. |
|
DETAILED DESCRIPTION The circuit embodiment of the present invention illustrated in FIG.
1 is implemented with a current transformer, specifically a differential current transformer, generally indicated at 10, having utility in personnel ground fault protective devices.
Thus, transformer 10 includes a toroidal core 12 through which a line conductor L and a neutral conductor N of a protected circuit pass as separate, single-turn primary windings.
Wound on this core is a multi-turn secondary winding 14, center-tapped at 14a.
One end of this secondary winding is connected to the collector of a switching transistor Q1, while its other end is connected to the collector of a second switching transistor Q2.
The center tap 14a is connected to a positive voltage bus 16 which, with ground bus 18, is connected to an appropriate supply voltage source.
The bases of transistors Q1 and Q2 are connected to a switching control network 20 operating under the control of transistor Q3 to provide a peak current controlled inverter.
For a detailed disclosure of inverters of this type, reference may be had to commonly assigned U.
S.
Pat.
Nos.
3,781,638 and 4,071,812; the disclosures of which being specifically incorporated herein by reference.
Basically, the switching control network 20 operates to alternately render transistors Q1 and Q2 conductive such that the supply voltage on bus 16 drives current through one half of secondary winding 14 and then the other half in alternating fashion.
The emitters of transistors Q1 and Q2 are connected together such that their emitter currents flow to the ground bus 18 through a common voltage divider consisting of resistors R1, R2 and R3.
The junction between resistors R2 and R3 is connected to the base of transistors Q3 through a resistor R4.
The collector of transistor Q3 is connected to switching control network 20, while its emitter is connected to ground bus 18.
From the description thus far, it is seen that while switching control network 20 renders transistor Q1 conductive and transistor Q2 non-conductive, the supply voltage drives current through the left half of secondary winding 14, the collector-emitter circuit of transistor Q1 and the voltage divider (resistors R1, R2 and R3) to ground bus 18
|
|
Audio Signal Processing 
