Abstract: A rechargeable energy storage includes a battery pack having a plurality of battery modules between a negative terminal and a positive terminal. A backup network is electrically connected between the negative terminal and the positive terminal. The backup network includes a first diode and a second diode. A bypass junction located between a first portion of the battery pack and a second portion of the battery pack. The bypass junction electrically connects the battery pack and the backup network. The backup network is configured such that current flow is directed along a first pathway when open circuit state occurs in the first portion of the battery pack, and the current flow is directed along a second pathway when the open circuit state occurs in the second portion of the battery pack. The backup network enables powering of a designated load and/or a designated function during the open circuit state.

Abstract: In an embodiment a thermal protection device includes a housing, a varistor partly embedded in the housing, wherein the housing electrically insulates the varistor, and wherein the varistor includes a partly uninsulated contact surface, an inner wall of insulating material arranged adjacent to the contact surface of the varistor, a window in the inner wall configured to allow an electrical connection of the contact surface of the varistor in an operational state of the thermal protection device and a moveable insulation block configured to cover the window in the inner wall to insulate the varistor in a region of the window of the inner wall in a fault state of the thermal protection device.

Abstract: A lightning strike fault monitoring system for a wind turbine generator system and a lightning protection system (110) thereof, wherein the lightning strike fault monitoring system for the wind turbine generator system includes the lightning protection system. The lightning protection system (110) comprises a main body (101) provided with a blind hole (1011), a core (102), a connecting member (103) made of gasifiable material, a first elastic member (104), a second elastic member (105), a sealing cover (106), a bottom plate (107), and a switch used for connecting between an external signal source and a detecting terminal. The core (102) and the first elastic member (104) are respectively accommodated in the blind hole (1011), and the core (102) is connected to the main body through the connecting member (103). One end of the first elastic member (104) abuts against the core (102), and the other end is connected to the bottom wall of the blind hole (1011).

Abstract: Provided are an open-mode protection device and an electronic device having the same. An open-mode protection device according to an embodiment of the present invention is connected in parallel to each of a constant current source and a load configured with a light emitting diode (LED). The open-mode protection device comprises a first external electrode connected to one sides of the constant current source and the load; a second external electrode connected to the other sides of the constant current source and the load, and a ground; a protection unit configured to bypass, to the ground through the second external electrode, an overvoltage or an overcurrent flowing into the first external electrode; and a current suppressing unit connected in series to the protection unit and configured to sense a temperature or current of the protection unit and reduce the current of the protection unit as the temperature or current increases.

Abstract: An electrical wiring system/method implementing transient voltage suppression is disclosed. The system/method incorporates HOT, NEUTRAL, GROUND wiring in conjunction with a series drop resistor (SDR) on the HOT conductor that supplies current to the load device. Parallel shunting metal oxide varistors (MOVs) are used in conjunction with corresponding shunt diode rectifiers (SDRs) to suppress transients on the HOT conductor to either the GROUND conductor and/or NEUTRAL conductor. The parallel shunting MOV/SDR pairs may be integrated into a singular structure that is encapsulated in an insulating material to permit implementation of the transient protection wiring system/method into electrical loads and common power distribution equipment such as electrical outlets and power strips.

Abstract: A surge protection device having a housing, two connections for connection to a current path to be protected, and at least a first discharge conductor in the housing. In a normal state of the device, the first connection is electrically conductively connected to the first connection region of the discharge conductor, and the second connection is connected to the second connection region by at least one component. A metal safety element, which has two contact regions and a connecting region which connects the contact regions to one another, is arranged within the housing. The first contact region is electrically conductively connected to the second connection region and the second contact region is electrically conductively connected to the component in the normal state. The connecting region is a fuse by which brief pulse currents can be transmitted by the connecting region, whereas mains-frequency short-circuit currents overload the connecting region destroying it.

Abstract: The present disclosure provides systems and methods for calculating the flux in a core of an unloaded power transformer using current measurements taken from a capacitance-coupled voltage transformer (CCVT) attached to the same phase line as the power transformer. According to various embodiments, the current sensors may both be positioned at zero-voltage points in the CCVT, eliminating the need for high-voltage insulated current sensors. An intelligent electronic device (IED) may determine the magnetic flux within the core of the power transformer using the measured and/or derived currents through capacitive assemblies of the CCVT. The IED may calculate the residual flux in the power transformer when it is de-energized. The IED may use the calculated residual flux to facilitate an optimized re-energization of the power transformer, thereby reducing inrush currents during re-energization.

Abstract: An electric circuit connected to a thermal switch with three terminals and a method for connecting the switch are realized. In an electric circuit of a common power supply, an external connection wire (first terminal) of a thermal switch arranged close to a current limiting resistor is connected to a load side (rectifier circuit), the current limiting resistor is connected between the external connection wire (first terminal) and an external connection wire (second terminal), and an external connection wire (third terminal) is connected to the output side of a power supply switch. Thus, the current limiting resistor is connected and arranged to an internal resistor unit of the thermal switch in series and to a switch unit (contact) in parallel.

Abstract: A fault-tolerant self-indicating surge protector system and methods are presented. An unwanted surge of electrical energy induced by a lightning strike is directed away from a sensitive electrical or electronic component, and the unwanted surge of electrical energy is directed through series connected pairs of varistors. A voltage signal is extracted from a center tap point between the series connected pairs of the varistors, and the voltage signal is monitored for a health of the varistors. A high impedance in a varistor among the varistors is provided for a low voltage across the varistor, and a low impedance in the varistor is provided and the unwanted surge of electrical energy is diverted through the varistor in response to a high voltage across the varistor.

Abstract: A voltage surge protection device for protection of a high voltage device includes a varistor having a first part and a second part separated by varistor material. The voltage surge protection device further includes an expandable member arranged to act on a movable electrical contact for short-circuiting the voltage surge protection device upon a threshold voltage being applied between the first part and the second part of the varistor. A high voltage circuit breakers includes one or more semiconductor devices connected in series and the voltage surge protection device connected in parallel thereto.

Abstract: A surge protection element includes a contact stud and a contact element disposed at a distance from the contact stud. A connection element is configured to be transferred into a first position, in which the connection element is applied to the contact stud and to the contact element so as to electrically connect the contact stud to the contact element, and into a second position, in which the connection element is disposed at a distance from the contact stud and the contact element. In the first position, the connection element engages at least partially around at least one of the contact stud and the contact element and a thermally separable connection is provided between the connection element and the contact stud and between the connection element and the contact element.

Abstract: An electronic protection component incorporates both a varistor and an alloy-type thermal fuse. In one embodiment, a melting promoting agent or flux contacts and surrounds both the varistor and the fuse in common in a shared cavity of a case. In another embodiment, the fuse and the flux are disposed in an inner case, which is disposed in contact with the varistor in an outer case. Thus, the varistor and the thermal fuse are incorporated so that the speed of heat transfer is fast, the response time is fast, and the installation for use is convenient.

Abstract: The invention relates to a surge arrester which, in a housing (7), has at least one arrester element (3), in particular a varistor, a solder-fixed thermal disconnection point (5), which is connected to the arrester element, and a damage indicating device (11) for displaying the fault state, wherein the damage indicating device also queries the state of a thermal disconnection device, in particular a fuse, and presents the possible fault states of the arrester element and of the disconnection device mechanically in an OR combination in a suitable way. Furthermore the thermal disconnection device comprises a movable component, which is fixed by an indicator wire and is released after the melting or destruction of said wire. According to the invention, a guide part (9) for a compression spring (10) or similar force accumulator is provided on or in the housing.

Abstract: A high-voltage surge arrester includes an electrically conductive first terminal and an electrically conductive second terminal longitudinally spaced from the first terminal. A plurality of metal oxide varistor (MOV) bars are included, each of which extends from the first terminal to the second terminal and electrically contacts the first terminal and the second terminal. A heat conducting material contacts the MOV bars.

Abstract: A voltage suppression device for suppressing voltage surges in an electrical circuit having a voltage sensitive assembly comprised of a plurality of tubular sections within a tubular casing.

Abstract: A surge arrester includes a short-circuit device. The short-circuit device includes at least one first base element. The first base element is rigidly connected in an electrically conducting and mechanical manner to a first electrode of the surge arrester. The short-circuit device also includes at least one spring arm arranged on the base element. The free end of the spring arm has a distance to the base element, and the spring arm extends over at least two adjoining electrodes of the surge arrester.

Abstract: A surge protector includes a thermal separating device and an error display, and at least two first protection elements, particularly disk-shaped varistors (7), and at least one second protection element, particularly a gas arrester (9), wherein the first and the at least one second protection elements are switched in a Y arrangement. The surge protector further includes a device housing for accommodating the protection elements, and structure, such as a spring (11), for the mechanical biasing of the thermal separating device, wherein the thermal separating device has a low-melting solder, and the first protection elements (7) are disposed in the device housing such that a connection arm of a protection element (7) is positioned opposite the connection arm of the further protection element (7) at a distance, and the thermal separating device is predominantly positioned in the distance space (13) formed in such a manner.

Abstract: A device for protecting against overvoltages that includes at least one overvoltage protection component (11); a thermosensitive member (17) capable of deforming, dependent upon the temperature thereof; a thermal connection between the at least one protection member and the thermosensitive member; and at least one mechanical member (15) for cooperating with the thermosensitive member and capable of cooperating with a system for triggering an electrical cut-off device (2). The thermosensitive member (17) and the at least one mechanical member (15) are arranged such that, when the thermosensitive member exceeds a given temperature threshold, the thermosensitive member, by reason of the deformation thereof, causes a movement of said at least one mechanical member (15) which correspondingly actuates the system for triggering the electrical cut-off device.

Abstract: An overvoltage protection element having at least one overvoltage limiting component in a housing, terminal contacts for electrical connection of the overvoltage protection element to a path to be protected, an electrically conductive connecting element and with a spring system acting on the connecting element, a first terminal contact being directly connected with the first pole of the overvoltage limiting component, the connecting element being in electrically conductive contact with the second terminal contact and the second pole of the overvoltage limiting component via a thermally separating connection. With the thermal connection separated, the connecting element moves out of electrically conductive contact with the second terminal contact and the second pole of the overvoltage limiting component by the force of the spring system an insulating disconnecting element connected to the connecting element is moved between the second terminal contact and the second pole of the overvoltage limiting component.

Abstract: A surge arrester is described which includes at least two electrodes. At least one of the electrodes includes a ventilation channel. The internal area of the surge arrester is connected to an external area of the surge arrester via the ventilation channel, wherein the ventilation channel is closed by means of a fusible element. The fusible element is preferably arranged at that end of the ventilation channel which faces the external area of the surge element.

Abstract: An electrical protection assembly for connection between an electrical power supply line and electrical equipment has an insulating mounting structure; a first arm connectable to a live conductor for connection to a fusible device at a first end and a voltage surge protection unit at a second end, pivotally attached to the mounting structure in a displaceable manner intermediate its ends; a first connection arrangement at the first end of the first arm for connection to the fusible device; and a second connection arrangement at the second end of the first arm for connection to the voltage surge protection unit. The assembly further includes first and second springs for urging the first arm relative to the mounting structure. The springs may urge the second connection arrangement towards the voltage surge protection unit and the first connection arrangement away from the fusible device.

Abstract: An overcurrent protective wire wound resistor has a core, a second contact cap and a resistance wire. A first contact cap and a resistor connection seat are respectively mounted on two ends of a rod of the core. A low melting-point conductive layer is mounted around the rod and connected with the first contact cap and the resistor connection seat. A high-temperature contractive insulation layer is mounted around the low melting-point conductive layer and the first contact cap. The second contact cap is mounted around the contractive insulation layer. The resistance wire is connected to the resistor connection seat and the second contact cap. When current through the resistance wire abnormally increases, high temperature of the resistance wire melts the low melting point conductive layer to shrink the contractive insulation layer and open the low melting-point conductive layer and the resistor, thereby protecting the circuit connected to the resistor.

Abstract: A thermally protected surge suppression device comprises a housing and a base seat with a mounting plate. The base seat is provided with a surge suppression component and a thermal protection device, and the thermal protection device further comprises a metal bulge electrically connecting to the electrode B of the surge suppression component, a compression spring, a slider provided with an arc extinguishing component movable on the guide-track groove. In normal working condition, the conductive metal member electrically connects to the metal bulge via a low temperature solder. When the surge suppression component fails, the low temperature solder is melt owing to being passed through the power frequency fault current, the conductive metal member is disconnected from the metal bulge, the compression spring pushes the arc extinguishing component to move to obstruct the disconnected gap, and form an airflow to extinguish the electric arc between the conductive metal member and the metal bulge.

Abstract: An electrical protection component with a short-circuiting device includes a surge arrester including at least two electrodes. The electrical protection component has at least one fusible element having a geometrical form including at least one cavity. A short-circuiting link is arranged at the surge arrester, wherein the short-circuiting link presses onto the fusible element. The short-circuiting link is spaced apart from the electrodes by means of the fusible element.

Abstract: A double-sided printed circuit board may include: electrical conductor tracks fitted thereon and serving for electrically connecting components mounted on the printed circuit board, which has at least one conductor track fuse in the form of a conductor track with a fusible link part, wherein, upon the occurrence of an abnormal operating state, in particular an electrical short circuit, the electric circuit is interrupted by melting and evaporation of the fusible link part and plasma arises upon the evaporation of the fusible link part, wherein the fusible link part lies on the other side of the printed circuit board with respect to the supply line.

Abstract: An electrical protection component with a short-circuiting device includes a gas-filled surge arrester that includes at least two electrodes. Preferably, one electrode in each case is arranged at the ends of the surge arrester. The electrical protection component has a thermal short-circuiting device, wherein the thermal short-circuiting device includes a clip having at least two sections. At least a first section of the clip is attached to the surge arrester by snap action. At least a second section of the clip at least partly surrounds the first section and is spaced apart from the first section by means of a fusible element. The second section has a short-circuiting link at an end. The short-circuiting link electrically connects the electrodes of the surge arrester to one another in the case where the fusible element melts.

Abstract: A varistor comprises a main body having first and second external terminals formed on the outer surface thereof, a first withdrawn terminal plate joined to the first external terminal, and a second withdrawn terminal plate joined to the second external terminal, wherein the melting point of a second bonding material for allowing the second withdrawn terminal plate and the second external terminal to be joined to each other is lower than that of a first bonding material for allowing the first withdrawn terminal plate and the first external terminal to be joined to each other.

Abstract: A protection circuit includes a surge absorber, a switch device electrically connected to the surge absorber and having a first conductor and a second conductor, and a heat-shrinkable device disposed on an outer periphery of the surge absorber and shrinking in accordance with temperature of the surge absorber. The first conductor has a first connecting portion and a second connecting portion. The surge absorber is connected to the first connecting portion. When the switch device is in an initial state, the second connecting portion electrically contacts the second conductor, and when the heat-shrinkable device shrinks to separate the second connecting portion from the second conductor, the switch device is switched off.

Abstract: A ZnO surge arrester for high-temperature operation is characterized in that a grain boundary layer between ZnO grains thereof contains a BaTiO3-based positive temperature coefficient thermistor material, which takes 10-85 mol % in the overall grain boundary layer, and when operating temperature raises, the positive temperature coefficient thermistor material in the grain boundary layer has its resistance sharply increasing with the raising temperature, so as to compensate or partially compensate decrease in resistance of components in the grain boundary layer caused by the raising temperature, thereby making the resistance of the grain boundary layer in the ZnO surge arrester more independent of temperature. The ZnO surge arrester thus is suitable for operation where a maximum operating temperature is higher than 125° C., or even higher than 150° C.

Abstract: A surge arrester includes a short-circuit device. The short-circuit device includes at least one first base element. The first base element is rigidly connected in an electrically conducting and mechanical manner to a first electrode of the surge arrester. The short-circuit device also includes at least one spring arm arranged on the base element. The free end of the spring arm has a distance to the base element, and the spring arm extends over at least two adjoining electrodes of the surge arrester.

Abstract: A surge protection device employing a controlled convection thermal disconnector in which a surge protective component, such as a metal oxide varistor, and a thermally responsive device, such as a thermal cut-off, are placed in separate, cross-ventilated chambers. An internal vent is positioned such that it prevents line-of-sight between the surge protective component and a mechanized portion of the thermally responsive device, in order to protect the thermally responsive device from hot surge protective component emissions from the surge protective component. An output vent is formed between the thermally responsive device and the exterior atmosphere to promote forced convective heat transfer from the surge protective component to the thermally responsive device during a thermal runaway condition, with the expanding gases in the surge protective component chamber providing the transfer impetus.

Abstract: A voltage surge protection device comprising a disconnection device with electric contacts said disconnection device comprising a first connecting electrode electrically connected with a first connecting strip, a second connecting electrode electrically connected with a second connecting strip, and a third switching electrode electrically connected to the second connecting strip. The protection device comprises a surge arrestor connected in series with a thermal disconnector between the third movable arc switching electrode and the second connecting strip. Said thermal disconnector comprises at least one fuse element extending between a first and second conducting radial wall of an arc extinguishing chamber, said arc extinguishing chamber comprising at least one conducting separator.

Abstract: A hybrid surge protector for a network interface device (NID) is disclosed. The hybrid surge protector includes a fail-safe spring connected to the ground electrode of a three-electrode gas tube. Tabs on the fail-safe spring are held away from the gas-tube end electrodes by a fusible element. The hybrid surge protector also includes metal-oxide varistor elements (“MOVs”) in contact with the gas-tube end electrodes and with the ground electrode via an MOV spring. This arrangement provides for two initial paths to ground-one path from the gas-tube end electrodes to the ground electrode through the gas tube, and another from the gas-tube end electrodes to the ground electrode through the MOVs and the MOV spring. The dominant path to ground starts as the MOV ground path but switches to the gas-tube path as the gas tube becomes activated. Another path to ground via the fail-safe spring is also available should the gas tube overheat.

Abstract: A circuit protection device for protecting a photovoltaic (PV) system from an overcurrent condition. The circuit protection device includes a first electrode electrically connectable to a first line of an electrical circuit, a second electrode electrically connectable to a second line of the electrical circuit. A first thermal element, second thermal element and an overload assembly define a first conductive path between the first and second electrodes. A bypass shunt defines a second conductive path between the first and second electrodes. The overload assembly electrically connects the first thermal element to the second thermal element, and is moveable between a closed position and an open position (i.e., overload condition). A low melt temperature solder electrically connects the overload assembly to the second thermal element. The low melt temperature solder softens and melts as the temperature increases in response to an overcurrent condition.

Abstract: At least one embodiment of the invention relates to a protective circuit for protection of an appliance, in particular of an electric motor, against thermal overloading. In at least one embodiment, the protective circuit includes a first and a second terminal for connecting a temperature detection element; a detection unit for detecting whether a resistance value of the temperature detector element which is connected between the first and the second terminals, is in a first or a second resistance range; a short-circuit detector for identifying whether there is a short circuit between the first and the second terminals; signaling outputs for emitting signal messages to an evaluation unit when the detected resistance value is in the second resistance range and/or when a short circuit has been identified by the short-circuit detector; and a third terminal, which is connected to the second terminal via a predetermined resistance.

Abstract: A surge arrester is described which includes at least two electrodes. At least one of the electrodes includes a ventilation channel. The internal area of the surge arrester is connected to an external area of the surge arrester via the ventilation channel, wherein the ventilation channel is closed by means of a fusible element. The fusible element is preferably arranged at that end of the ventilation channel which faces the external area of the surge element.

Abstract: A device for detecting lightning strikes (9) on an electrically insulating structure (11) likely to be subjected to a lightning strike, for example an aircraft radome, includes on an external surface (12) one or more lightning arrester strips (10), made of an electrically conductive material and electrically linked to an electrically conductive structure. At least one inductive sensor (3) is positioned near the internal surface (13) of the electrically insulating structure so that the inductive sensor delivers a signal when a lightning arrester strip is passed through by a lightning current I. The signals from the inductive sensor, for example a flat coil or two flat coils mounted in opposition, are received and processed by acquisition means.

Abstract: One embodiment of the present invention is a compliant thermal contactor that includes a resilient metal film having a plurality of first thermally conductive, compliant posts disposed in an array on a top side thereof and a plurality of second thermally conductive, compliant posts disposed in an array on a bottom side thereof.

Abstract: In a composite electrical circuit protection device, thermal coupling between a planar PPTC element and a planar MOV element is controlled by insertion of a thermal mass material for regulating heat transfer from the MOV element to the PPTC element, such that a PPTC resistor hot zone forms consistently away from the planar major foil electrode confronting the MOV thereby regulating heat transfer from the MOV to the PPTC resistor.

Abstract: The invention relates to an automatically quenching surge arrester arrangement with a surge arrester, which, on exceeding a given first voltage, transforms from a non-conducting into a conducting state and returns to the non-conducting state only when a much smaller second voltage is dropped below and with a switch mechanism reacting to current flow through the surge arrester, interrupting the current flow through the surge arrester and then automatically returning to the rest condition thereof. A simple, robust and compact assembly suitable for HF applications for such a surge arrester arrangement is achieved, whereby the switch mechanism reacts reversibly to the heat generated in the surge arrester by the current flow.

Abstract: A device (1) for protecting an electrical installation (2) from overvoltages, including at least one protection component (3), and disconnection element (4) capable of ensuring the electrical disconnection of the protection component from the installation by moving from a closed configuration to an open configuration, wherein the device (1) has at least one first fuse element (7) and one second fuse element (8) capable of holding the disconnection element (4) in the closed configuration, and wherein the disconnection element (4) includes at least one first contact surface (4A) and one second contact surface (4B) substantially intersecting with one another and to which the first and second fuse elements respectively adhere when the disconnection element (4) are in the closed configuration, to distribute the stresses exerted on the fuse elements and reinforce the mechanical strength of the disconnection element.

Abstract: A varistor including a varistor body with two parallel end faces made of a material that contains one or more metal oxides, and at least one electrode made of an electrically conductive electrode material arranged on any of the end faces of the varistor body. The electrode includes a layer of electrode material coated on the end face by means of an ion- or atom-transferring method, whereby the layer has a thickness within the interval of from 5 micrometers to 30 micro-meters.

Abstract: An electric device generates a predetermined amount of heat in the event of a malfunction. The electric device is protected from overheating in that it is arranged, with a fuse in a circuit, such that the fuse and the electric device are thermally coupled to one another, so that the generation of the amount of heat by the electric device causes a material in the fuse to melt. In this manner, the current terminal path of the electric device is interrupted.

Abstract: An integrated fuse device (1) includes a varistor stack (11), a thermal fuse (12), and a current fuse (13) within an enclosure (2) having device terminals (3). The varistor stack (11) is connected to the thermal fuse (12) by a Cu terminal (20) and is connected to the device terminal (3) by steel terminal (10) of smaller cross-sectional area. Being of Cu material and having a greater cross-sectional area, the terminal (20) connected to the thermal fuse (12) has greater thermal conductivity than the steel terminal (10) to the end cap (3). The thermal fuse (12) comprises a plurality of links having a melting point to melt with sustained overvoltage, the links having a diameter in the range of about 2 mm to about 3 mm. The links pass through an elastomer plug (15), which exerts physical pressure on them to assist with opening during sustained overvoltage. Hot melt (18) around solder (17) of the thermal fuse limits heat conduction to back-fill sand.

Abstract: A thermal trip device in which a bimetal (2) is heated by overcurrent and performs trip operation of a circuit by curvature of the heated bimetal (2), wherein at least one part of the surface of the bimetal (2) is made to be black or matte black (7). Thereby, temperature of the bimetal (2) can be highly accurately measured using a no-contact thermometer. Furthermore, a temperature measurement part (8) of the bimetal is provided with a bending part (11), and the surface of the bending part is made to be matte black.

Abstract: One embodiment of the present invention provides a system that detects changes in power-supply current within an integrated circuit (IC) chip. During operation, the system monitors an induced current through a detection loop. This detection loop is situated at least partially within the IC chip in close proximity to a power-supply current for the IC chip, so that a change in the power-supply current changes a magnetic field passing through the detection loop, thereby inducing a corresponding current through the detection loop. The system then generates a control signal based on the induced current, so that changes in the power-supply current cause the control signal to change. In addition, the system uses the control signal to control circuits within the IC chip.

Abstract: A circuit protection device including a conductor arm releasably connected between a voltage sensitive device and a circuit to be protected. The connector arm is biased to move in a direction generally parallel with a plane defined by a lateral dissection between the releasably connected conductor arm and the voltage sensitive device.

Abstract: A surge arrester includes an outer electrode and an other electrode. An electrically conductive contact element is spaced apart from the outer electrode by an air gap. The electrically conductive contact element is pretensioned by a spring mechanism that exerts a spring force on the contact element in the direction towards the outer electrode. An electrically conductive connection is located between the other electrode and the contact element. The air gap between the outer electrode and the contact element is arranged in a tightly enclosed hollow space.

Abstract: A motor controller includes: an estimated temperature calculating section that calculates and stores an estimated temperature of a motor, and a control section that can perform a drive control of the motor only when this estimated temperature is not larger than a predetermined value. When the motor is stopped, a second temperature gradient while the temperature of the motor decreases from a stop-time temperature to a predetermined first set temperature is stored in correspondence to the stop-time temperature. The first temperature gradient corresponding to the estimated temperature at a time when the motor is stopped is calculated by using the first temperature gradient storing means, if the estimated temperature stored in the estimated temperature storing means when the motor is stopped is larger than the first set temperature.

Abstract: A voltage suppression device for suppressing voltage surges in an electrical circuit, comprised of a voltage sensitive element having a predetermined voltage rating, the voltage sensitive element increasing in temperature as voltage applied across the voltage sensitive element exceeds the voltage rating. Terminals are provided for electrically connecting the voltage sensitive element between a power line of an electrical circuit and a ground or neutral line of the electrical circuit. A normally closed, thermal switch is electrically connected in series with the voltage sensitive element between the power line and the voltage sensitive element, the thermal switch being thermally coupled to the voltage sensitive element wherein the thermal switch moves from a normally closed position to an open position to form a gap between the thermal switch and the voltage sensitive element when the temperature of the voltage sensitive element reaches a level indicating an over-voltage condition.