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Showing papers on "Isolation transformer published in 1969"


Patent
10 Oct 1969
TL;DR: In this paper, the authors describe a ground integrity detector circuit with two voltage stepdown transformers connected in series with one another and with the sensor, which is intended to be connected to a remote ground terminal as well as the ground terminal of the line voltage source.
Abstract: A circuit for use with a sensor located in a hazardous area such as in an atmosphere of explosive gases, organized to prevent electrical power at the sensor from exceeding prescribed levels even upon reasonably foreseeable failures of parts of the circuit. The circuit, which is located in a nonhazardous area, includes an indicator, such as a relay-controlled alarm, to respond to the sensor, and terminals for connection to a source of line voltage. Two voltage stepdown transformers have their secondaries connected in series with one another and with the sensor. The primary of one transformer is connected to the line voltage source; and the primary of the other transformer is connected to the indicator. Each transformer secondary lies intermediate a pair of current-limiting resistors, and the primary and secondary windings of each transformer are isolated by means of a grounded conductive sheet. Each transformer, along with its associated current-limiting secondary resistors, is embedded in potting material to form a self-contained isolating circuit module. The circuit is intended to be connected to a remote ground terminal as well as the ground terminal of the line voltage source. A ground integrity detector circuit interrelates these three terminals by means of resistances and a neon glow tube is provide a signal whenever one of the ground circuits is lost, as well as a signal upon failure of one of the resistances forming the ground integrity detection circuit. The remote ground connection has a path extending through the circuit chassis to insure that its ground is maintained.

52 citations


Patent
12 Mar 1969
TL;DR: In this paper, a control signal is generated in response to the change in the power transferred from the input side of a transformer to the output side of the transformer by the controller.
Abstract: A SYSTEM DETECTS CHANGES IN THE OUTPUT VOLTAGE ON THE INPUT SIDE OF A TRANSFORMER USED BY THE SYSTEM AND GENERATES A CONTROL SIGNAL IN RESPONSE TO THE CHANGE FOR CHANGING THE POWER TRANSFERRED TO THE OUTPUT SIDE OF THE TRANSFORMER. THE INPUT AND OUTPUT HAVE GROUND ISOLATION. AS A RESULT OF CONTROLLING THE POWER TRANSFERRED TO THE OUTPUT SIDE, THE OUTPUT VOLTAGE IS MAINTAINED AT A CONSTANT LEVEL.

38 citations


Patent
23 Jun 1969
TL;DR: A transistorized electrical sleep-inducing device includes a current regulating buffer which protects the patient from excessive current, when operated on conventional AC power and maintains the current substantially constant regardless of variations in the patient's body resistance as discussed by the authors.
Abstract: A transistorized electrical sleep-inducing device includes a current regulating buffer which protects the patient from excessive current, when operated on conventional AC power and maintains the current substantially constant regardless of variations in the patient's body resistance. The patient is also protected by sensitive fuses, an isolation transformer, careful grounding, a floating circuit and a substantial resistance connected in series with him. A peak reading volt meter precisely indicates the pulse amplitude by utilizing a peak detector circuit connected to a high input impedance, such as balanced bipolar transistors or a unipolar field effect transistor (FET) differential amplifier. A frequency band selector and scanner, connected to the pulse generator, varies the applied frequency to suit the patient's response. The output is contacted to various portions of the patient's anatomy in accordance with his particular symptoms and treatment therefor.

32 citations


Patent
10 Feb 1969
TL;DR: In this article, a pair of switching transistors, serially connected across a common DC source, have a junction returned to one of the source terminals through the primary of an output transformer in series with a control transformer and with a frequencyselective network which includes a blocking capacitor and discriminates against frequencies above a predetermined switching frequency established either by the network itself or by a tuned secondary circuit of the control transformer.
Abstract: A pair of switching transistors, serially connected across a common DC source, have a junction returned to one of the source terminals through the primary of an output transformer in series with the primary of a control transformer and with a frequencyselective network which includes a blocking capacitor and discriminates against frequencies above a predetermined switching frequency established either by the network itself or by a tuned secondary circuit of the control transformer.

22 citations


Patent
05 Jun 1969
TL;DR: In this article, the primary windings of a main and an auxiliary transformer are coupled across an AC input line, and a single-pole, single-throw switch interposed in one conductor of the input line subsequent to auxiliary transformer takeoff point permits deenergization of main transformer primary winding without interrupting energization of auxiliary transformer primary woundings.
Abstract: In a solid state television receiver, the primary windings of a main and an auxiliary transformer are both coupled across an AC input line. A single-pole, single-throw switch interposed in one conductor of AC input line subsequent to auxiliary transformer takeoff point permits deenergization of main transformer primary winding without interrupting energization of auxiliary transformer primary winding. One secondary winding of main transformer provides AC input to television receiver power supply. Kinescope filament is energized by circuit comprising a secondary winding of auxiliary transformer in series with an additional secondary winding of main transformer. When switch is closed, receiver is ''''on'''' with power supply operative and kinescope filament receiving full rated voltage comprising sum of secondary contributions. When switch is open, receiver is in ''''standby'''' condition- with power supply inoperative, but kinescope filament energized at reduced level representing contribution of auxiliary transformer secondary alone. In remote control embodiment, auxiliary transformer has additional secondary winding providing AC input to remote control receiver power supply.

19 citations


Journal ArticleDOI
01 Jan 1969
TL;DR: In this paper, a mathematical model is set up for foil-wound transformers, and the current density is obtained as the solution to an integral equation, a method of solution suitable for use on a digital computer is outlined.
Abstract: In foil-wound transformers, the width of the foil used in one winding is generally the full winding height of the transformer so that the current density is nonuniform. A mathematical model is set up for such transformers, and the current density is obtained as the solution to an integral equation. A method of solution suitable for use on a digital computer is outlined.

18 citations


Patent
12 Jun 1969

14 citations


Patent
Valdis E. Garuts1
28 Jul 1969
TL;DR: In this paper, a diode is placed in series between the switching transistor and the transformer primary such that the transistor conducts substantially no current at times during predetermined half-cycles of oscillator operation, but the transistor is switched by feedback to an on condition during each nonconducting half-cycle whereby it will deliver current to the transformer in a zero voltage condition.
Abstract: A regulated oscillator circuit for producing a predetermined high voltage output employs a switching transistor for supplying current to a high-voltage transformer and for receiving feedback current from the same high-voltage transformer. A diode is placed in series between the switching transistor and the transformer primary such that the transistor conducts substantially no current at times during predetermined half-cycles of oscillator operation. However, the transistor is switched by feedback to an on condition during each nonconducting half-cycle whereby it will deliver current to the transformer in a zero voltage condition. The period during which current is delivered to the transformer is determined by a control circuit which turns off the transistor at a selected time during each cycle of operation in accordance with the output level produced. A voltage doubler circuit is driven by the transformer and provides a DC output level.

10 citations


Patent
Nathan Swerdlow1
27 Jan 1969
TL;DR: In this article, a power system in which first, second and third single-phase transformers have their primary windings connected in delta is described, where a spare transformer is disposed physically adjacent to the third transformer and is provided with switching means for connecting its primary winding to the bus in a manner that enables the spare to serve as a replacement for the third transformers.
Abstract: Discloses a power system in which first, second and third single-phase transformers have their primary windings connected in delta. A spare transformer is disposed physically adjacent the third transformer and is provided with switching means for connecting its primary winding to the bus in a manner that enables the spare to serve as a replacement for the third transformer. Additional switching means is provided for connecting the primary winding of the third transformer to the bus in a way that enables the third transformer to serve as a replacement for the second transformer, should such replacement be necessary. Still additional switching means is provided for connecting the primary of the second transformer to the bus in a way that enables the second transformer to serve as a replacement for the first transformer, should this latter replacement be necessary.

9 citations


Patent
10 Nov 1969
TL;DR: In this paper, a transformer is provided with a protective circuit which serves to switch in a protective damping burden on the transformer in the presence of transient oscillation phenomena, and the circuit connections between the transformer primary and the intermediate capacity section include a choke coil and a low-ohmic blocking coil to improve the transformer for coupling high frequency signals to the line for carrier type communication.
Abstract: A capacitive voltage transformer comprises a transformer having its primary winding connected across an intermediate section of a plurality of capacity sections connected in series between a high voltage line and ground to form a voltage divider. The transformer is provided with a protective circuit which serves to switch in a protective damping burden on the transformer in the presence of transient oscillation phenomena, and the circuit connections between the transformer primary and the intermediate capacity section include a choke coil and a low-ohmic blocking coil to improve the transformer for coupling high frequency signals to the line for carrier type communication.

6 citations


Patent
07 Aug 1969
TL;DR: In this paper, the secondary winding of an exciting transformer inserted between the central point of the series transformer and the earth is replaced with a tertiary winding to control the voltages of the respective power systems.
Abstract: An interconnecting apparatus for electric power systems wherein two electric power systems are connected to each other with a series transformer and the secondary winding of the series transformer is energized with a compensating voltage whose value and polarity are such that it cancels the voltage drop developed across said transformer when said electric power systems are normally operating. The compensating voltage is derived from the secondary winding of an exciting transformer inserted between the central point of the series transformer and the earth. The secondary winding of the series transformer is connected in delta and the secondary winding of the exciting transformer is star-connected. If it is necessary, the exciting transformer may be provided with a tertiary winding to control the voltages of the respective power systems by the voltage of this tertiary winding.


Patent
03 Jan 1969
TL;DR: In this paper, a high frequency magnetron apparatus for use in heating ovens with an improved power source device which comprises a transformer for stepping up a source voltage, a magnetron disposed on the secondary side of the transformer, and a circuit consisting of a condenser and diode was arranged in such a manner that when there is supplied a voltage in one direction from the poser source provided on the transformer and when there was supplied a voltages therefrom in the opposite direction, the secondary voltage of transformer is combined with the charge voltage of the condenser to be impressed on the magnet
Abstract: A high frequency magnetron apparatus for use in heating ovens with an improved power source device which comprises a transformer for stepping up a source voltage, a magnetron disposed on the secondary side of the transformer, and a circuit positioned on said secondary side, consisting of a condenser and diode and arranged in such a manner that when there is supplied a voltage in one direction from the poser source provided on the secondary side of the transformer, the condenser is charged and that when there is supplied a voltage therefrom in the opposite direction, the secondary voltage of the transformer is combined with the charge voltage of the condenser to be impressed on the magnetron.

Patent
20 Oct 1969
TL;DR: In this paper, isolation transformers are employed to provide direct current isolation of the analog output signal of a digital-to-analog converter from the digital input signals and the digital computer power supply.
Abstract: Isolation transformers are employed to provide direct current isolation of the analog output signal of a digital-to-analog converter from the digital input signals and from the digital computer power supply The converter contains buffer storage elements, digital-to-analog switches, and a ladder network to retain the last computer output signal indefinitely in case of computer breakdown or failure of the computer power supply An analog controller can be employed to provide a continuous correction to the last computer control signal represented by the converter output, in the event the computer fails or is shut down for repair

Patent
24 Oct 1969
TL;DR: In this paper, a maximum current indicator to monitor the current flow in an electrical apparatus is presented, where a facsimile of load current from a current transformer is applied to a heater resistor, such that the steady state temperature of the sensor is directly proportional to the power dissipated in the heater.
Abstract: A maximum current indicator to monitor the current flow in an electrical apparatus. A facsimile of load current from a current transformer is applied to a heater resistor. A sensor resistor having a high positive temperature coefficient is coupled to the heater such that the steady state temperature of the sensor is directly proportional to the power dissipated in the heater, making such temperature a function of the facsimile load current. The sensor resistor is part of a voltage divider network which includes a rheostat, the voltage across such divider being determined by a Zener diode. The divider output voltage at a junction thereof is determined by the sensor resistor and the rheostat. A pair of transistors are arranged in an emitter coupled binary circuit whose conduction states are determined by the voltage at the junction of the divider network. An isolation transformer and a silicon controlled rectifier form a switching circuit which is actuated by the binary circuit. A motor is controlled by the switch, the motor acting to set an indicator dial and also to drive the rheostat to a position for resetting of the binary circuit.

Patent
29 Apr 1969
TL;DR: In this article, the number of gate-constrained, gate-consistent, and gate-controlled, switchboard-switching devices in a three-phase TAP-CHANGING TRANSFORMER system is minimized by simultaneously USing the same STATIC SEMICONDUCTOR SWitching DeVICES in COMBINATION with APPROPRIATE SWITCHING DEVICES HAVING RELATIVELY MOVable CONTACTS.
Abstract: THE NUMBER OF GATE-CONTROLLED SEMICONDUCTOR A-C SWITCHING DEVICES (INVERSE PARALLEL CONNECTED THRYSTORS OR TRIACS) IN A THREE-PHASE TAP-CHANGING TRANSFORMER SYSTEM IS MINIMIZED BY SEQUENTIALLY USING THE SAME STATIC SEMICONDUCTOR SWITCHING DEVICES IN COMBINATION WITH APPROPRIATE SWITCHING DEVICES HAVING RELATIVELY MOVABLE CONTACTS FOR SEQUENTIALLY EFFECTING TAP-CHANGING OPERATIONS IN ALL THREE PHASES OF A Y-CONNECTED TRANSFORMER WHOSE WINDINGS ARE TAPPED.

Journal ArticleDOI
TL;DR: In this article, it was shown that the speed of response of a pulse-current transformer is mainly limited by the propagation delay along the secondary winding, and that the response speed of a transformer is limited by propagation delay.
Abstract: It is shown that the speed of response of a pulse-current transformer is mainly limited by the propagation delay along the secondary winding.

Proceedings ArticleDOI
01 Sep 1969
TL;DR: In this paper, the problem of designing the coils for a large power transformer is one of great complexity, in addition to the obvious parameters of operating voltage and current, impedance and losses, the designer must consider many other requirements, including the ability to withstand various types of impulse voltage waves and the mechanical strength to resist stresses resulting from short-circuit conditions.
Abstract: The problem of designing the coils for a large power transformer is one of great complexity. In addition to the obvious parameters of operating voltage and current, impedance and losses, the designer must consider many other requirements, including the ability to withstand various types of impulse voltage waves and the mechanical strength to resist stresses resulting from short-circuit conditions. A requirement which is always present is that of maximum reliability. At the same time it is essential that the size, weight and cost of the finished transformer be as small as possible.

Patent
19 Nov 1969
TL;DR: An electric furnace for arc melting having electrodes connected to a main source of electrical power is provided in this article. But the transformer is a three phase transformer and there are a plurality of power factor correctional devices connected to the high voltage winding of each phase of the transformer.
Abstract: An electric furnace for arc melting having electrodes connected to a main source of electrical power. A transformer having high voltage windings and low voltage windings is provided. There is means for independently connecting the electrodes to the low voltage windings of said transformer, and means for connecting the high voltage windings of the transformer to power factor correctional devices. The transformer is a three phase transformer and there are a plurality of power factor correctional devices connected to the high voltage winding of each phase of the transformer. The power factor correctional devices are preferably capacitors. Circuit breakers are provided for connecting the capacitors to the high voltage windings and disconnecting them therefrom and for changing the amount of capacitance connected to the high voltage windings.

Journal ArticleDOI
TL;DR: In this paper, an estimate of the losses in superconducting transformer windings is made, and it is shown that if these are not to be excessive, the transformer has to have a large rating.

Journal ArticleDOI
TL;DR: In this paper, a simple direct current transformer is described for applications where a low cost device is required for an existing heavy current or high voltage installation where interruption of, or electrical contact with, the main load circuit is undesirable.
Abstract: This paper describes a simple direct current transformer which utilizes the switching action of reed relays which have their coils fed from a separate alternating current supply. The transformer is shown to be particularly suitable for applications where a low cost device is required for an existing heavy current or high voltage installation where interruption of, or electrical contact with, the main load circuit is undesirable. Operation of the new transformer is fundamentally based on Ampere's law for the closed path integration of magnetizing force around a current carrying conductor, and its theoretical response is shown to be polarity sensitive and independent of the auxiliary supply voltage, but dependent on supply frequency. In practice, the transformer is shown to be substantially unaffected by the limited variations of frequency and voltage which are associated with a normal a.c. supply. A complete range of test results, which includes temperature effects, is given for a 5000 A transformer and methods of range extension are indicated. An attractive feature of the new transformer is that the analysis of its basic response is extremely simple and leads to a theoretical performance which is closely followed in practice.

Patent
18 Mar 1969
TL;DR: In this article, an isolating transformer is described for transmitting AC electrical power from a power-supply circuit at ground potential to a load circuit which is at DC high voltage; the transformer comprises a single transfer loop equipped with insulation which withstands the DC voltage.
Abstract: An isolating transformer is described for transmitting AC electrical power from a power-supply circuit at ground potential to a load circuit which is at DC high voltage; the transformer comprises a single transfer loop equipped with insulation which withstands the DC voltage, which loop is inductively coupled to a first of said electrical circuits by way of a magnetic circuit completely surrounding the said turn, and inductively coupled to the other of said electrical circuits and at DC potential thereof.

Patent
18 Jul 1969
TL;DR: In this paper, a radiation-hardened pulse-producing system having an oscillator, a buffer amplifier and a saturable core transformer for producing output pulses is described, including blocking oscillators, to insure at least a predetermined time delay between output pulses will be maintained.
Abstract: A radiation-hardened pulse-producing system having an oscillator, a buffer amplifier and a saturable core transformer for producing output pulses. Current feedback loops from the output winding of the transformer to the input winding of the transformer, including blocking oscillators, insure at least a predetermined time delay between output pulses will be maintained if the system is subjected to a radiation environment.