Abstract: A visual and audible alarm are connected to a control circuit for an oil well pumping unit. The control circuit includes a time clock which controls the intermittent ON-OFF cycle of operation of the pumping unit in the automatic mode, the OFF portion of the cycle allowing the well to recover pressure. The audible and visual alarm operates through a time delay relay connected to the time clock to provide a warning to people in the vicinity of the pump of the imminent start-up of the pump before allowing the pump to start, thereby providing people in the area the opportunity to avoid injury by evacuating the area.

Abstract: A protective time delay delay circuit delays energization to an electric load until a predetermined time has elapsed from a previous deenergization. A transistor has its emitter connected to an ac conductor and has its base coupled to an RC timing circuit. The collector is connected to the gate of a triac whose current electrodes are coupled to the thermostat conductor and to a load device. A small resistor and a zener can be connected to the transistor to provide brownout protection. A temperature sensitive resistor can be included to increase or decrease the lockout period as a function of temperature. This resistor can be remotely mounted in thermal proximity to the load to be protected. A thermistor placed in parallel to latching capacitor can provide thermal overload protection.

Abstract: An air-conditioner comprises a refrigerating circuit having a compressor, a condenser, an expansion device and an evaporator which are connected by suitable refrigerant conduits. An electric current path for making a current flow through the compressor includes an AC power source, to which a current transformer is coupled, and an output of the current transformer is converted into a DC voltage which is then given as a (+) input of a comparator. A reference voltage is given to a (-) input of the comparator. When the DC voltage exceeds the reference voltage of the comparator, the high level is outputted from the comparator. When the high-level output from the comparator persists for three seconds, the compressor is stopped forcedly and a three-minute timer is turned on. After a lapse of three minutes, the flow of the current through the current path of the compressor is resumed. Thereby, a lightly locked state is removed.

Abstract: A highly efficient over current circuit breaker for an electric system is provided with a timer which is adjustable and can be set to produce a first control signal a predetermined time after the electric system is turned on, and a load detector in association with an over current control device which produces a second control signal when the load applied to the electric system exceeds a predetermined level. The first control signal and second control signal jointly activate an amplifier to produce a third control signal which activates relays to cause a magnetic switch to open, or "trip", whereby the electric system is turned off. The timer allows an electric surge to occur in the electric system without causing the magnetic switch to trip during the period of starting the electric system. The circuit breaker is particularly useful in systems having induction motors in which starting current surges are common.

Abstract: An apparatus is provided for controlling an electric motor that is doing some sort of work, whereby the apparatus automatically senses the presence of a work overload. Once the work overload is sensed, the apparatus automatically reverses the direction of rotation of the motor to eliminate the work overload. The reversed rotation is limited to either a predetermined period of time or to a predetermined number of reverse rotations. Once the predetermined limit of reverse rotation is reached, the apparatus automatically resumes normal rotation of the motor.

Abstract: An electronic starting motor control system for electric starting apparatus of a type that has a solenoid including a solenoid coil. Energization of the solenoid coil causes solenoid contacts to close and causes a pinion to be shifted into mesh with the ring gear of an engine to be cranked. The current supply to the solenoid coil is controlled by a plurality of parallel connected field effect transistors that are turned on and off. The system has a fail safe circuit which operates to cause the wire bonds of the field effect transistors to open in the event that a field effect transistor fails by shorting. The system has an overvoltage protection circuit which during an overvoltage condition shuts off the supply of voltage to the gates of the transistors and shuts off the voltage supply to a plurality of control circuits that are coupled to the gates of the transistors.

Abstract: A motor controller is adaptable to a wide range of motor currents by using an integrator circuit having an additional feedback arrangement for affecting the effective time constant of the integrator under specified conditions. The operational amplifier has an amplifier having a first input, a second input, and an output, an input resistor connected between an input of the operational amplifier and the first input of the amplifier, and a feedback impedance connected between the output of the amplifier and the first input of the amplifier. A voltage at the input of the operational amplifier is compared with a voltage at the first input of the amplifier. An auxiliary current path for the feedback impedance is provided when the voltage at the input of the operational amplifier has a predetermined relationship to the voltage at the input of the amplifier.

Abstract: A system for use with electrical machines allows fast transfers to be made from one power source to another or fast reconnections to be made to a momentarily interrupted power source without subjecting the machines to unsafe voltage levels. The system short circuits the electrical machines to bring their residual voltage down quickly to a level at which the machines may be safely connected to a power source, and works with both induction and synchronous machines. No interlocking devices are necessary to the system, thus further speeding up fast transfer while minimizing the effects of inadvertent direct short circuiting of the power source.

Abstract: Refrigeration system control systems and methods for protecting a refrigerant motor/compressor, for example in an air conditioner, against conditions of excessive loading. The systems and methods of the invention recognize and distinguish between conditions of high operating load and insufficient condenser airflow, and take appropriate action for each. High operating load conditions are responded to by providing a motor/compressor cool-down interval, followed by a restart, so that an air conditioner remains operating at its maximum capacity, consistent with the field conditions. Insufficient condenser airflow conditions are responded to by eventually terminating operation of the motor/compressor until, for example, a service technician is called. Operation is based on a recognition that excessive loading conditions are manifested much sooner when the cause is insufficient condenser airflow than when the cause is a high operating load.

Abstract: Calibrated methods and systems for protecting refrigerant motor/compressors against overload and loss of refrigerant conditions, independent of compressor and system size, while avoiding the need for a plurality of sensors. The disclosed methods and systems are generic in the sense that they may be employed in a variety of different air conditioner or heat pump models of different sizes and capacities, without being specifically tailored for a particular model, although a factory calibration adjustment is required. The disclosed methods and systems sense loading on the compressor motor, and make control decisions based thereon. A permanent compressor motor reference loading is established when the refrigeration system has a known correct refrigerant charge and the motor/compressor has a known load. This is typically accomplished in the factory after a predetermined stabilization interval has elapsed following initial start up of the motor/compressor.

Abstract: A motor protection relay is provided which is programmable to limit the number of starts which are allowed in a given interval of time. In accordance with the algorithm associated with the relay microprocessor for controlling the starts per time, old starts which no longer fall within the same time constraint set by the operator or user are discarded and the time constraint is updated according to the next oldest start time.

Abstract: A motor protector having a thermostat metal element thermally coupled to an electrical motor in a refrigerator compressor motor system has a heater responsive to motor current thermally coupled to the thermostat metal element and has an improved component arrangement to provide locked rotor and ultimate trip protection for the motor without requiring calibration of the operating temperature for the protector after assembly or after incorporation in the motor system.

Abstract: Protection of induction motors and generators is provided to allow rapid reclosure of the power supply or fast transfer from one power supply to an alternate supply. A switching sequence is disclosed in which motor stator windings are short circuited immediately following interruption of the supply voltage. Said short circuit quickly discharges to a safe value the energy stored in the rotor of the induction machine, allowing the short circuit to be removed and safe reconnection to the power supply to be accomplished without further delay.

Abstract: A motor protector having a thermostat metal element thermally coupled to an electrical motor in a refrigerator compressor motor system has a heater responsive to motor current thermally coupled to the thermostat metal element and has an improved component arrangement to provide locked rotor and ultimate trip protection for the motor without requiring calibration of the operating temperature for the protector after assembly or after incorporation in the motor system.

Abstract: Motor control circuits having fault protection devices are in commercial use today. Such devices typically include logic elements requiring a conditioned power supply, and are incapable of operation directly from the main motor power supply. The subject apparatus includes a timing circuit for monitoring the electrical conduction of a power switching element associated with an electrical motor. The apparatus produces a fault signal in response to the power switching element continuing to conduct for longer than a predetermined continuous period of time. A latch receives the fault signal and responsively produces a blocking signal. An interrupt circuit receives the blocking signal and responsively controllably blocks power from the motor power supply to the electrical motor. Each of the timing, latch, and interrupt circuits is adapted to operate directly from the motor power supply and independent of any intermediate logic power supplies or associated logic devices.

Abstract: An engine starter has a plunger electromagnetically actuated by holding and attracting coils to move a pinion toward a ring gear on the engine and also to move a first movable contact on the plunger towards first and second stationary contacts to be electrically connected together by the first movable contact to electrically energize a starter motor. A relay is provided and has normally open contacts electrically connected in series to a power source and the connection between the holding and attracting coils. The relay coil is connected in series to a starter switch and a temperature sensor. The temperature sensor is formed by a normally closed switch having a third stationary contact connected to the relay coil, and a bimetallic element carrying a second movable contact grounded through the bimetallic element.

Abstract: Disclosed are refrigeration system control systems and methods for compressor motor protection and defrost control. The disclosed systems and methods are generic in the sense that they are self-calibrating and so may be employed in a variety of different air conditioner or heat pump models of different sizes and capacities, without being specifically tailored for a particular model. The disclosed systems and methods sense loading on the compressor and evaporator fan motors, preferably by sensing the voltage across the capacitor-run winding of an AC induction motor and normalizing with respect to line voltage. The self-calibrating capability is implemented by taking advantage of the changing loads as a function of time on both the compressor and fan motors during both normal and abnormal operation of a refrigeration system. In overview, a reference value of motor loading is established for each motor at certain times during an ON cycle.

Abstract: An electrophotographic copying machine including some corona dischargers each having a high voltage transformer and an abnormal condition detection device. The abnormal condition detection device includes a detection unit for detecting an output level at a secondary winding of the transformer, an input unit for inputting an input voltage to a primary winding of the transformer. A comparator is provided for comparing the output level on the detection unit with the input level on the input unit, and outputting a detection signal. A control circuit of the copying machine is responsive to the level of the detection signal for controlling the operation of the copying machine.

Abstract: A stall detection method for electric induction motors and apparatus utilized the stator current and voltage phase difference as proportional to percentage synchronous motor speed, and detects a stall condition from this speed as a parameter of motor movement. The invention includes differentiating the phase difference to obtain motor acceleration as a parameter potentially indicative on its own, or in conjunction with phase difference, of a motor stall condition.

Abstract: A motor controller receives a signal proportional to motor current, integrates that signal during the high currents associated with starting, and holds a level during normal operation at speed within a maximum current limit. When an overload causes the motor to trip and there is a loss of power to the controller, a memory holds the level for a predetermined time to prevent an immediate restart of the motor.

Abstract: A refrigeration system alarm device includes a temperature monitoring circuit which detects when a temperature within the refrigeration system exceeds a preselectable temperature reference level. The device also includes an alternating current power monitor circuit which detects when any one of a plurality of alternating current power inputs is interrupted. The device also includes a direct current power monitor circuit which includes a battery and a comparator circuit for determining when the voltage of the battery is below a predetermined level. When an excessive temperature is detected or an alternating current power input interruption is detected or the battery voltage is below the predetermined reference level, a visual or audible alarm signal is generated.

Abstract: A motor protector of the type having a snap acting thermostatic element is shown particularly adapted for use with compressor motors in which a conventional three pin header is mounted on the compressor casing to allow electrical energization of the motor. An improved heat transfer path is formed between the windings of the motor and the thermostatic element of the protector by suspending the protector from one of the motor pins in optimum heat conductive relation therewith and thermally separated from the compressor casing and any component mounted on the other two pins.

Abstract: A system for protecting the starter of an internal combustion engine from overheating as a result of cranking for an excessive period of time when the engine is difficult to start. Override circuitry is electrically interposed between a manually operable starter switch and the engine starter to apply a prescribed ON and OFF cranking sequence to the starter and thereby limit the duty cycle even though the operator continuously operates the switch. Preferably, the overall maximum duration of the start attempt (the duration of the ON and OFF cranking sequence) is limited by termination circuitry. The ON and OFF cranking intervals and, optionally, the overall maximum duration of the start attempt are particularly selected so as to allow sufficient time for motor winding heat to dissipate into the starter housing. This limited cranking duty cycle protects the starter from overheating.

Abstract: A microprocessor controlled motor starter is utilized in which an operator can preprogram within limits the number of starts which a motor can be subjected to in a programmed period of time to thus prevent destruction of the motor by accumulated overheating. Significantly more heat is generated during a start of a motor than during the run mode. The foregoing is accomplished by utilizing memory locations in which accumulated times from a first start are sequentially stored in order. If the time found in the latest memory location is larger than the predetermined maximum allowable time then the start is allowed to take place. If it is less than that time then the start is prevented from taking place and a readout alerts the operator as to how much time must expire before the next allowable start may take place.

Abstract: An improved electromagnetic relay having a wafer of material with positive temperature coefficient of resistivity (PTC) mounted inside the relay combines a sturdy construction with low manufacturing costs adapting the relay for use as a starting relay for electric motors of compressors. For this purpose, the magnetic members of the relay are incorporated in the electrical relay circuit and are provided with attachments for plug-on connections of the relay to circuit pins of motor-compressor units.

Abstract: A combination starter-protector device for a winding circuit of a dynamoelectric motor comprises a housing structure having a perforated wall dividing the interior of the housing structure into starter and protector compartments. The starter compartment accommodates therein a positive temperature coefficient thermistor while the protector compartment accommodates therein a bimetal switch. The housing structure has two sets of terminals, one set of the terminals being adapted to be connected to the winding circuit of the motor whereas the other set of the terminals are adapted to be connected to a power source. The distance between the thermistor and the bimetal switch may be adjustable by the employment of a spacer element.

Abstract: There is disclosed a protective system for preventing damages to a tool and a work or tool changing mechanism component parts due to any interference between the tool and the work during the tool changing operation by an automatic tool changing apparatus in a numerical control machine tool such as a machining center.The protective system monitors the load current of a driving motor for the automatic tool changing apparatus, whereby when the load current reaches an abnormally high current value during the operating period excluding the motor starting period, the operation of the automatic tool changing apparatus is reversed and then stopped.

Abstract: A thermoswitch is physically located on a portion of the current supply connector between the current source and the exciter winding of the starter motor. The portion, constructed as a simple strip with flaps holding the thermostat, influences the temperature-dependent control portion of the thermoswitch according to heating in the armature, field winding, and brushes of the starter motor. The thermoswitch turns OFF the starter system by interrupting current supply to the kick-in starter relay.

Abstract: A method of assembling a combination starter-protector device and mounting it in a preselected assembly position onto at least a pair of plug terminals associated with a housing having a dynamoelectric machine arranged therein and with the at least plug terminal pair connected in circuit relation with a winding circuit of the dynamoelectric machine. The combination starter-protector device includes a pair of separable casing members, a PTCR, an overload protector, and at least a pair of female terminals. In this method, the PTCR, the protector device and the at least female terminal pair are enclosed within the casing members, and a resilient means is releasably secured generally about a major peripheral portion of the casing members for retaining them against separation.

Abstract: A motor control system includes a motor system having a pole-amplitude-modulated (PAM) motor, a motor breaker, and a speed switch coupled between the motor breaker and the PAM motor. The PAM motor is coupled to a fan in an exhaust duct having a controlled damper for controlling air flow therethrough. A control system step logic sequencer includes means responsive to permissive signals for providing in sequence control signals to the motor breaker and speed switch in response to confirmation signals received from the motor breaker, the speed switch and the PAM motor.

Abstract: This invention relates to a system for protecting an amortisseur winding during the starting of a synchronous motor. The system compares the actual slip frequency of the accelerating motor with predetermined slip frequencies. These predetermined slip frequencies are each associated with a timer which measures successive time segments. Each timer is stopped when the actual slip frequency, which decreases as rotor speed increases, is less than the associated predetermined slip frequency. When the timer is stopped a successive timer is started. In this manner the acceleration of the motor is broken up into time segments. The initial timer is started when the motor starts. The final timer is stopped when the rotor field current is applied to bring the motor into synchronism. Should any timer be permitted to have its timed segment expire before being stopped, the motor is shut down. There is also provided a thermal memory which receives information from the expired timer as to its associated slip frequency.

Abstract: An alarm circuit is interlocked with the start circuit of power driven industrial machinery such as a coal tipple so that before the machinery can be started, an alarm must be energized for a predetermined time to alert personnel that the machine is about to start. In the event that the machinery is not started within a predetermined time after termination of the alarm, or in the event that the alarm has not actually sounded, the whole cycle must be repeated.

Abstract: A motor starting relay particularly adapted for use in starting single phase asynchronous motors comprises a resistor element of positive temperature coefficient of resistivity which is compactly arranged within a housing and engaged by electrical contact and terminals means of particular structure and of a material of relatively high thermal resistance in a novel way such that power dissipation or loss by the resistor is reduced to a very low level after it has performed its motor starting function but so that, at the same time, the resistor is adapted to cool more rapidly after interruption of motor operation to permit prompt motor restarting.

Abstract: A housing is disclosed in which a positive temperature coefficient (PTC) of resistivity element is mounted a selected distance from but in thermal communication with a thermostatic switch also mounted within the housing.

Abstract: A compact resistor device comprises a body of ceramic material of positive temperature coefficient of resistivity having a large number of passages extending through the body between opposite ends of the body, thereby forming very thin webs of the resistor material between adjacent passages. Coatings are formed on the resistor material along the inner walls of the passages to serve as ohmic contacts. The coatings in alternate passages are connected together at one end of the resistor device and the coatings in the other passages are connected together at the opposite end of the device to serve as device terminals. When the device terminals are connected to a power source, current flows through very thin webs of resistor material between ohmic contacts in adjacent body passages. The resistor device is particularly useful in current limiting applications requiring low, room-temperature resistance and in heat-exchanger applications where a fluid to be heated is directed through the passages.

Abstract: A solid state electronic circuit for protecting a single phase induction motor against excessive loading by comparing motor start winding voltage with motor source voltage is disclosed, wherein the circuit automatically removes the motor from its driving source upon the occurrence of such excessive loading. An additional feature includes comparing start winding voltage with source voltage to remove the motor from its driving source upon the occurrence of excessive start winding voltage and corresponding excessive high motor speed. A motor starting circuit to permit the start winding voltage to rise to its normal running level and a time delay restarting circuit to permit the motor to automatically restart after elapse of a selected lock out period following removal of the motor from the source due to insufficient or excessive loading is also provided.

Abstract: There is disclosed a squirrel-cage motor for a winch drive or other application and control means for operating the motor in hoist or lower directions at any one of a plurality of speeds in either direction. The motor and winch are provided with a load brake. In one embodiment, the stator comprises two stator windings having different numbers of poles to provide high speed (fewer poles) and low speed (more poles) windings. The control means comprises a direct current power source, an alternating current power source, means for connecting the sources to the stator windings so that different speed points and braking operations are achieved, and means for operating the load brake. Low speed results from simultaneously energizing the low speed winding and the high speed winding from the alternating current power source and the direct current power source, respectively. Intermediate speed results from energizing only the low speed winding from the alternating current power source.

Abstract: Control apparatus is provided for a contactor which has a coil and at least one pair of contacts movable from an open position to a closed position in response to energizing the coil. The control apparatus includes apparatus for temporarily and permanently energizing the coil and switching apparatus for controllably energizing the coil.

Abstract: An alarm circuit is interlocked with the start circuit of power driven industrial machinery such as a coal tipple so that before the machinery can be started, an alarm must be energized for a predetermined time to alert personnel that the machine is about to start. In the event that the machinery is not started within a predetermined time after termination of the alarm, the whole cycle must be repeated.

Abstract: A method of protecting auxiliary winding means and main winding means in a winding circuit of a dynamoelectric machine in the event of a current overload. In this method, means is actuated in response to a preselected thermal condition accompanying the current overload for interrupting the winding circuit. Heat is transmitted from means for controlling starting of the dynamoelectric machine to the interrupting means for generally maintaining the winding circuit effectively interrupted for at least a predetermined period, and the starting controlling means is operable generally in response to current flow therethrough to increase its resistance generally as a function of its temperature for impeding the current flow therethrough to the auxiliary winding means at a preselected speed of the dynamoelectric machine.A combination starter-protector device, a method of operating a dynamoelectric machine, and a circuit are also disclosed.

Abstract: A controller for a motor or like electrical equipment. A thyristor in series with a power conductor that feeds the equipment and a control circuit for activating the gate terminal of the thyristor in accordance with the operating conditions of the equipment. The control circuit includes a transformer having a secondary winding connected to the gate terminal and means for varying the current flow in the secondary winding according to load demands. A three phase system having a thyristor in each conductor and a transformer secondary winding for each thyristor, which windings are on a common core.

Abstract: A motor is electrically coupled to a power source through a motor starter. The motor starter is selectively operated by a relay to connect and disconnect the power source to the motor. A counter is set whenever a select motor temperature condition exceeds a predetermined level to provide an indication of the number of motor starts. The relay is operated to cause the motor starter to disconnect the power source from the motor whenever the motor fails to run continuously during a given time period following a predetermined number of starts.

Abstract: Apparatus for the prevention of undesirable and possibly hazardous automatic application of power to a load in the event of an outage from a power source and a subsequent re-application of power therefrom. Described is a thyristor type of circuit interrupter coupled into a control circuit which is operative to control the operation of phase-controlled SCR circuit which is cyclically operative to couple power from an AC power source to a load device such as a DC motor. In the preferred embodiment, an SCR circuit interrupter is coupled into the DC supply circuit of a control circuit comprising, inter alia, a pulse generator which provides trigger pulses which are applied to a pair of silicon controlled rectifiers in the phase-controlled SCR circuit.A two-pole, two-position switch is adapted in one (STOP) position to couple the AC power source to the SCR circuit interrupter which includes means for being latched, i.e.

Abstract: A motor control circuit for controlling the operation of a motor having main running-speed windings and also start-up windings includes a fixed time delay circuit to energize the main windings after a time delay following energization of the startup windings. In addition a lock-out circuit is provided to prevent re-start of the circuit following a particular fault condition.

Abstract: A control circuit for a motor usable in a refrigeration system has a variety of condition sensors including means to sense a low refrigerant pressure and timing means to override the sensing of low refrigerant pressure for a time period during motor start-up. A lockout circuit prevents re-start of the motor following a fault condition.

Abstract: A motor protection circuit has a current sensing means connected in series with a contactor winding energization circuit for sensing current flow to initiate operation of a delay after break circuit or to maintain an oil pressure protection circuit unoperated.

Abstract: A control circuit, such as a motor control circuit, includes a capacitance connected at one side with a timing resistance to the gate of a field effect transistor (FET) which inhibits energization of a load, such as a motor. The FED controls a semiconductor switch which is connected by a diode to the other side of the capacitance to prevent reactuation of the circuit during a time delay determined by the rate of current flow through a timing resistance to the one side of the capacitance.

Abstract: A protection system for an electric motor including a safety switch to deenergize the motor upon the occurrence of a potentially deleterious operating condition. The protection system includes a current sensitive device in series with the motor. The device is deenergized when the motor is deenergized due to the occurrence of the deleterious operating condition. The protection system further includes a holding device having a normally closed switch electrically connected thereto. The holding device is energized and its switch is opened when the current sensitive device is energized. The holding device remains energized, even though the current device is deenergized, to prevent the motor from being reenergized. The holding device is deenergized to permit reenergization of the motor by the manual opening of a switch connected in series therewith.