Abstract: A refrigeration system associated with a conditioned space to be controlled to a predetermined set point temperature via heating and cooling cycles. The refrigeration system includes a fluid flow path through which a predetermined fluid is circulated. The fluid flow path includes first, second and third heat exchangers. The first heat exchanger is disposed to condition air of the conditioned space, the second heat exchanger is in heat exchange relation with cryogenic cooling apparatus, and the third heat exchanger is in heat exchange relation with heating apparatus. The first and second heat exchangers are interconnected when the conditioned space requires a cooling cycle, and the first and third heat exchangers are interconnected when the conditioned space requires a heating cycle. Cryogen of the cryogenic cooling apparatus is thus not expended to heat the conditioned space, nor used for defrosting purposes.

Abstract: A synchronous machine is protected from closely spaced instances of excessive field current and an excessive volts/hertz ratio by a control system which models rotor and stator cooling to provide memory of recent periods of excessive heating. Maximum excitation limiting and volts/hertz ratio limiting modules in a microprocessor based automatic voltage regulator for the machine generate time delayed limit signals which override voltage feedback control when the respective parameters exceed threshold values. The limiters each increment a count when the associated threshold value is exceeded and generate the associated limit signal when a predetermined count is reached. The predetermined counts and the counting rates are selected such that the delay intervals are inversely proportional to the amount by which the threshold values are exceeded. The counts are decremented at a rate which models rotor and stator cooling when the respective parameters return below the threshold values.

Abstract: A molded case circuit breaker includes an interlock which prevents the operating handle from being moved from the on position after the main contacts have been welded together. By preventing the operating handle from being moved from the on position during such a condition, the operating handle will indicate the correct status of the main contacts and the operator will be made aware that the main contacts are welded together.

Abstract: An elongated retainer member pivotally mounted on the auxiliary contact operating mechanism of a drawout circuit breaker maintains a positive connection for the mechanism with the channel assembly of the motion transfer assembly which actuates auxiliary contacts mounted on the cabinet wall of metal-clad switch gear.

Abstract: Methods and apparatus for monitoring and controlling the operation of a refrigeration unit in a manner which eliminates the need for circuit breakers and fuses in control circuits which are instrumental in selecting and changing the operational mode of the refrigeration unit. When a need to change to a different operating mode is detected, a controller energizes a control device associated with the different operating mode and quickly determines if the current draw is within an acceptable range. If the current draw is within an acceptable range or window, the controller initiates the requested different operating mode. If the current draw is not within the acceptable range, the controller generates an appropriate alarm and different courses of action are decided upon which depend upon whether the current draw is above or below the limits of the acceptable range, the nature of the requested operating mode, and the desired temperature of a space conditioned by the refrigeration unit.

Abstract: Microprocessor based apparatus for controlling an electrical load, such as a motor, includes an external capacitor for storing an analog equivalent of a digitally modeled heat state signal, such as the I.sup.2 t characteristic of the motor. The voltage on the capacitor decays to mimic motor cooling when the microprocessor is powered down with deenergization of the motor. The stored analog signal is updated by periodically converting the analog signal to a retrieved digital heat state signal which is compared to the latest calculated value of the heat state signal. If the retrieved value is below the present calculated value, an input/output port is set to a high output state to charge up the storage capacitor. If the retrieved value is above the calculated value, the port is configured as an output port with a low state to reduce the voltage on the capacitor.

Abstract: An ion mobility sensor for obtaining measurements of concentrations of constituents of multicomponent gaseous samples. The sensor having an ionization region into which the sample is entered connected to a drift region, the regions being separated by a grid electrode. A first electrode is disposed at an end of the ionization region opposite to the grid electrode. A collector electrode is provided at an end of the drift region opposite to the grid electrode and DC voltages are applied by the electrodes so as to create a unidirectional field across the sensor. A pulse of UV light is directed toward the grid electrode. A voltage pulse of selected magnitude is superimposed at the first electrode within the pulse width of the UV pulse. Ions characteristic of the sample travel through the grid electrode, across the drift region to the collector electrode. The electrical output in accordance with any ions received at the collector electrode is then measured.

Abstract: The tensioned jaws of a fuse clip are spread by a rotating a pin that rests in a slot in each of the jaws. The pin has opposed flat surfaces that define a position at which the jaws are not spread. The pin has a flange that rests in the slots, holding the pin in a fixed orientation.

Abstract: The rotation of a power control arm on a fuse box is used to rotate a contact, sequentially disconnecting power to a fuse and spreading the tensioned jaws on a fuse clip to reduce the force needed to remove a flat fuse terminal from the clip.

Abstract: A positive off mechanism for a circuit breaker includes a pair of positive off levers slideable in slots in the side plates and extendable into the path of the operating handle to prevent movement of the handle to the off position when the contacts are welded closed. The positive off levers are actuated by positive off links pivotally mounted to the side plates and coupled to the positive off levers by "dog bone" connections. The positive off links in turn are actuated by the toggle mechanism of the circuit breaker which collapses to open the contacts during normal circuit breaker operation, but which remains erect when the contacts are welded closed.

Abstract: A system for compensating for changes in pressure and temperature in an ion mobility sensor has first and second electrodes positioned a selected distance apart, with a unidirectional electric drift field provided between the electrodes. An ionization source generates ions in the sensor and a trigger controller allows ions to enter the region between the first and second electrodes at a time t.sub.1. A time t.sub.2 at which a selected ion species travels to one of the first and second electrodes is measured and a time to amplitude converter generates a voltage signal proportional to the difference between t.sub.1 and t.sub.2, representing the actual travel time of the ion species.

Abstract: A ground fault circuit breaker has line and neutral bus bars extending through the center apertures of two laterally spaced toroidal coils to form the primaries of ground fault sensing transformers. The bus bars have flat center sections extending between the two coils parallel to the coil end faces and offset laterally by flat laterally extending legs at each end which are bent transverse to the end faces of the coils and extend through the coil apertures in flat confronting relation. The leg on one end of the neutral bus bar has a terminal portion bent into a plane parallel to the center section with a crimp at the end for attachment to a neutral pigtail.

Abstract: A method of operating a refrigeration unit to improve the uniformity of temperature distribution in a conditioned space, with the refrigeration unit including a refrigerant compressor and an evaporator fan driven at a selectable one of high and low operating speeds by a prime mover arrangement. The method includes the step of periodically operating the compressor and evaporator fan at the higher of the two operating speeds, notwithstanding a set point temperature control algorithm calling for operation of the compressor at the lower of the two speeds. When the refrigeration unit is operating in a continuous mode, the value of a constant entered into an operating program by the user determines the minimum number of minutes of each hour the prime mover should be forced to operate in the higher speed mode.

Abstract: A pair of lock links straddling and pivoted on the same pin as the latchable cradle of a circuit breaker follow the toggle device of the breaker either by riding on the toggle knee pin or through a pin which bears against the edges of the toggle arms. The lock links have extensions which engage the handle yoke to prevent the handle from being moved to the off position when the circuit breaker contacts are welded closed causing the toggle device to remain erected.

Abstract: A microprocessor used in solid state products has multiple interrupts and a single read only memory (ROM) masked for two or more product programs. The logic state of an input pin is set to select the appropriate program. If there is an error in one program or it becomes obsolete, the microprocessor does not have to be scrapped, but can be used to execute the other (another) product program. Separate interrupt selection routines for each interrupt, addressed from a common interrupt vector table, direct program execution to an interrupt branch table for the product indicated by the input pin. The product branch table contains addresses for the interrupt service routines for the selected product. The product programs are first separately linked with the interrupt branch table for the corresponding product.

Abstract: Insulating barriers for flat, confronting C-shaped bus bars with facing, depending end portions are integrally formed with a pair of confronting C-shaped insulating members conforming to the shape of the bus bars and joined by a pair of projections extending between and electrically insulating the facing, depending end portions from each other. Preferably, the insulating barrier is formed with flat linear sections joining the confronting C-shaped members which are then folded to form the projections. The C-shaped insulating members have edge extensions covering the edges of the bus bars. Grippers formed integrally with the edge extensions snap under the bus bars to secure the insulating members in place.

Abstract: An integrated circuit incorporating an analog-to-digital (A/D) conversion subsystem having a current mode in which only negative analog currents are converted and a voltage mode in which only positive analog voltages are converted is adapted to produce bipolar digital current and voltage signals. An on-board microprocessor operates the A/D conversion subsystem to perform a conversion in the current mode. If the converted digital value is non-zero, this value is used as the negative digital value of analog input signal. If the result of the conversion in the current mode is zero, a second conversion is made in the voltage mode and used as digital value with a positive polarity. An input circuit having an output impedance substantially equal to the "full scale equivalent" input impedance of the IC defined as the full scale voltage of the IC divided by the full scale current, eliminates the need for special scale factors to correlate the positive and negative conversion values.

Abstract: A method for the identification of whether a lubricant in a compressor is an alkylbenzene or a naphthenic oil. This method comprises adding 3,3-bis (p-hydroxyphenyl) phthalide and observing whether there is an absence or presence of turbidity.

Abstract: A refrigeration system which controls the temperature of a conditioned space to a predetermined temperature range adjacent to a selected set point temperature SP via a cooling cycle which includes evaporation a cryogen, such as CO.sub.2 or N.sub.2, in a heat exchanger. In an apparatus embodiment, a controller determines a desired evaporation vapor pressure value EPX of the cryogen as a function of the selected set point temperature SP, and then controls the evaporation pressure EP in the heat exchanger means as a function of the determined desired evaporating vapor pressure value. The controller further determines a desired superheat value SHX of the cryogen exiting the heat exchanger means as a function of the selected set point temperature SP, and controls the mass flow rate of liquid cryogen evaporating in the heat exchanger as a function of the determined desired superheat value.

Abstract: Methods and apparatus for controlling a conditioned space to a predetermined set point temperature, utilizing a supply of cryogen. Cryogen is drawn from the supply in a flow path to provide a cooling mode via a heat exchanger disposed in the flow path. A vapor motor in the flow path, downstream from the heat exchanger, drives a fan which moves air between the conditioned space and the heat exchanger. Heat is applied to the cryogen downstream from the heat exchanger, after all cooling modes have been performed, to provide the desired fan horsepower, without interfering with a cooling cycle. A by-pass flow path selectively directs cryogen directly to the vapor motor, by-passing the heat exchanger, to provide air circulation in the conditioned space when the temperature of the conditioned space is satisfied.