Abstract: A circuit breaker has a phase selecting circuit for selecting one phase among plural phases, in which the largest current flows. After selecting the largest phase, the judgement whether an accidental overcurrent flows or not in executed by using only output signals from the selected largest phase.

Abstract: A circuit breaker having three level discriminating circuits and time-current operating circuits, respectively corresponding to an instantaneous releasing, a short time characteristic releasing and a long time characteristic releasing of disconnectable contacts.

Abstract: An improved current-sensing arrangement and method are provided for supplying a signal that suitably represents line current over a wide current range. The current-sensing arrangement utilizes the signals from an iron core transformer and an air core transformer along with transition and scaling arrangements to provide the sensed current signal. The range of operation includes currents for which the iron core transformer exhibits saturation effects and currents for which the air core transformer does not contribute to the combined output signal. Additionally, the range of operation includes currents for which both the transformers contribute to the combined output signal.

Abstract: Electronic trip units employed within static trip circuit breakers are individually calibrated and automatically adjusted to ensure that the trip transfer characteristics are within specification requirements. A trimming network within the trip unit circuit contains a plurality of parallel resistors each separately connected within the circuit by means of a fusible link. Test input and output values are compard to idealized values that are binary-weighted within a look-up table in the test equipment computer. The percent correction required is determined and the appropriate links are interrupted to provide ideal trip response.

Abstract: A digital solid-state trip unit of an electrical circuit breaker is equipped with an electrical contact wear indicator enabling the degree of wear of these contacts to be known. Each time the circuit breaker performs a break, the microprocessor determines a contact wear value, in terms of the maximum value of the current broken. The correspondence between the wear value and the current broken is stored in a ROM memory and the successive wear values are added in a NOVRAM memory whose contents are representative of the degree of contact wear. These contents can be displayed to indicate to the user that the condition of the contacts has to be checked.

Abstract: An inverse-time relay is disclosed which comprises a voltage dividing circuit for dividing a d.c. voltage proportional to a current value in a line to be protected by a plurality of ratios different from one another thereby to provide a plurality of voltage values, a voltage saturating circuit for saturating each of the divided voltage values at a predetermined value, and a microcomputer for achieving an inverse-time operation employing the plurality of voltage values obtained from the voltage dividing circuit. The microcomputer makes comparison between each of the plurality of the voltage values obtained from the voltage dividing circuit and the saturation voltage as to whether or not the former is smaller than the latter, and, for the divided voltage smaller in magnitude than the saturation voltage, counts the operating time corresponding to that voltage and delivers a decision output when the count has reached the operating time.

Abstract: A timer controlled multipole circuit breaker has a pair of breaker contacts in each pole which are connected to load and line terminals respectively provided in the current path of each pole. Incorporated in the breaker is electric timer for controlling to open and close the breaker contacts according to a predetermined timing schedule. The electric timer has its input end connected across the line terminals of the adjacent poles so as to be energized by the common power on the line terminals of the breaker without requiring any additional external wiring. The circuit breaker incorporating the electric timer of the present invention further provides a safeguard which inhibits the automatic reclosing of the contacts by the timer operation until the fault current condition is cleared.

Abstract: A circuit interrupter includes a circuit arrangement for sampling a conditioned current value and determining operating characteristics related to the current flow through an electrical circuit. Also included is a circuit arrangement for comparing the operating characteristics to preselectable tripping parameters and initiating a trip condition when an operating characteristic exceeds a corresponding tripping parameter. Additionally, a fault indicating and selecting arrangement which utilizes a trip curve graph to assist in the operation of the circuit interrupter, is also included.

Abstract: An instantaneous solid-state trip device has two threshold values providing an upper and a lower tripping threshold. A current increase rate detector determines, when a short-circuit occurs, the prospective peak current value and, if the peak value corresponding to the electrodynamic withstand of the circuit breaker is liable to be exceeded, causes a change of threshold to bring about tripping, as soon as the lower threshold is exceeded. This high-speed tripping favours short-circuit current limiting. When a short-circuit of a lesser importance occurs, the current variation is lower and the instantaneous trip release only trips when the upper threshold is exceeded. In most cases, this upper threshold is not reached and tripping selectivity can be easily achieved in the usual way. A break in the circuit connecting the sensor to the trip unit also causes the circuit breaker to trip.

Abstract: A fast acting solid state AC circuit breaker includes a power transistor module in series with a load. Load current is continuously monitored and compared with threshold current values which define maximum current for equipment turn-on and steady state conditions. The steady state conditions may be briefly exceeded to allow normal transient overloads to exist on the line for periods up to 25 milliseconds. A maximum current level greater than the normal transient overload can exist on the line for 10 milliseconds after the circuit breaker turns on. The circuit breaker can be turned off in less than 10 microseconds.

Abstract: Microprocessor-based solid-state trip unit (48) processing digital signals derived from analog signals supplied by current sensors (16). The analog signals are applied to a calibration circuit (34), which adapts the output range of the analog circuits to that of the logic circuits, to obtain with an 8-bit Analog-to-Digital Converter (50) associated with a Multiplexer (29) a range equivalent to that of 12-bit processing systems.

Abstract: Circuit protection and protective relay functions are provided by common circuit elements under the control of a single processor unit. Voltage and current values are obtained on a continuous basis and these values are continuously monitored within the processor to determine the electrical status of a protected power distribution system. Upon the occurrence of an overcurrent or undervoltage condition, the circuit is interrupted by operation of a circuit breaker trip solenoid causing the breaker contacts to open. When the overcurrent or undervoltage condition ceases to exist, the circuit breaker contacts could be closed by operation of a controlled relay. The ROM and RAM storage elements within the processor unit are continuously tested and the circuit breaker contacts are opened upon indication that the ROM or RAM element is nonfunctional.

Abstract: A trip signal generator comprises a circuit possessing an inverse time-current characteristics for producing a trip signal in response to the occurrence of overcurrent in an alternating current line. The trip signal is produced after the passage of some time period, which varies inversely with the difference between the absolute magnitude of the overcurrent and a threshold current. The circuit includes a portion which produces pulses at a rate proportional to the difference between the absolute magnitude of the overcurrent in the line and the threshold current. The circuit produces no pulses when the line current is less than or equal to the threshold current. The circuit includes a counter for counting the pulses and for producing the trip signal after the counting of a selected number of pulses. Another portion of the circuit enables the counter when overcurrent is in the line, but resets the counter and prevents its operation when the line current is less than or equal to the threshold current.

Abstract: Input/output circuitry is disclosed for use in an I/O system of a programmable controller. The circuitry is protected against overcurrents without the use of fuses or circuit breakers, and is automatically restored to normal operation following correction of an overload condition. Diagnostic signals are produced for monitoring the operating condition of the circuitry. The invention includes an insulated gate transistor (IGT) having a main current section carrying a majority of the load current and an emulation section which carries a fractional portion of the load current. The emulation section current tracks the total current at all times. A current sensor monitors the emulation section current and provides a signal representing the instantaneous load current. This signal is continuously compared with preselected reference levels to derive a set of diagnostic signals that are indicative of the operating condition of the circuit, and whether output loads are open or shorted, for example.

Abstract: A surge voltage protection arrangement for a load 10 connected to an A.C. supply 8 comprising a gas-filled excess voltage arrester 11 connected in series with a capacitor 12 across the load 10. The value of the capacitor 12 is chosen such that the largest expected surge pulse which causes the arrester 11 to fire will not charge the capacitor to such an extent that the voltage then applied across the load 10 exceeds that of the A.C. supply 8. The arrangement enables the arrester 11 to recover after such a surge pulse within a fraction of an A.C. supply cycle, thus avoiding placing an unnecessary load on the arrester. A resistor 13 whose resistance is of a value such that the capacitor 12 is able to discharge through it within one half cycle of the A.C. supply may be connected across the capacitor 12.

Abstract: A power controller with overload protection having an alternating current source (AC) connected through power lines (L1, L2) and a pair of power switching devices (FET1, FET2) and a current sensor resistance shunt (SH) in series to a load (LD). A line-derived control power supply circuit (LDS) is connected through one of the power switching devices (FET1) to the lower line (L1, L2) such that the control power supply current does not flow through the shunt (SH) or the load (LD). Close and open commands are applied from a control switch (CSW) through a threshold detector (DT) and a logic circuit (LG1) to operate a latch (LCH) that turns the power switching devices (FET1, FET2) on and off under the clocking control of a zero voltage detector (ZVD) and a zero current detector (ZCD) and the gating control of a minimum current circuit (MCC). An overload circuit (AVC, ITC, TTC) provides instantaneous trip of the latch on rupture current or timed trip of the latch on smaller overloads.

Abstract: A bus differential relay which is capable of distinguishing between an internal bus fault and an external fault on a feeder line with saturation of the faulted feeder line current transformer during portions of the alternating current cycles thereof is disclosed. The relay generates a net current signal or differential signal from the signals generated by the feeder line current transformers of the protected bus section. During an internal fault, the current differential signal extends in amplitude beyond fault current limits and a trip signal is generated to interrupt current to the bus section. During an external fault with current transformer saturation, the current differential signal will include amplitude portions of the alternating current cycles which exceed the fault limits.

Abstract: A current sensing transformer useful for sensing overload current with static trip units is fabricated from an inexpensive array of transformer core laminations and a conventional secondary transformer winding. The transformer primary strap is arranged about the secondary winding for improved flux transfer.

Abstract: Digital implementation of the overcurrent determination and time delay before tripping in a static circuit breaker trip unit allows the trip unit circuit to be manufactured in a single chip configuration. The signal after A/D conversion is compared within a magnitude comparator to determine pickup. A pulse stream proportional to the square of the overcurrent signal is developed by multiplying the outputs of two magnitude comparators which compare the A/D level with a continuous binary count. The time delay determination is obtained by means of 3 cascade connected divide by two counters with their outputs connected to a data selector, or by a rate-limiter circuit which uses a fixed frequency to gate a pulse stream proportional to the overcurrent level squared.

Abstract: A fail-safe device for removing power from controlled circuitry upon the occurrence of an undesired operating condition is disclosed. The fail-safe device includes means for detecting a short circuit in the controlled circuitry and for indicating the existence of an undesired operating condition if a short is detected. The fail-safe device further includes a non-volatile memory for retaining data through a power outage so that the existence of an undesired operating condition is remembered upon return of the power. The data stored in the non-volatile memory may also be useful in investigating an accident or malfunction. The fail-safe device still further includes a reset button which returns power after an undesired operating condition if it is momentarily depressed.

Abstract: A control circuit is provided for applying energy to operate a circuit interrupter in response to, and a selected time after, the onset of overcurrent in an alternating-current line. The control circuit includes a transducer for producing output current proportional to the current in the line. The power supply includes an energy storage circuit that stores energy derived from the output current. The stored energy, which is maintained within a first range when there is no overcurrent in the line, energizes the power supply. A time-current trip signal generator circuit responds to output current representative of moderate overcurrent in the line by producing a trip signal after the passage of a time period that is inversely related to the overcurrent.

Abstract: The analog electronic trip device comprises a time-lag tripping circuit formed by a non-linear function generator likely to elaborate by approximation the tripping characteristic of the circuit breaker.The device includes an integrating amplifier comprising a negative-feedback capacitor C and two inputs in phase opposition. One of the inputs is submitted to two threshold voltages V.sub.R1, V.sub.R2 determining the mode of long-time delay or short-time delay operation of the trip device. The second threshold voltage V.sub.R2 is set by a resistive switch which determines the short delay tripping threshold.

Abstract: A circuit breaker with a high linearity is provided which detects a current in a main circuit in a low current region by means of a current transformer, while the current in a high current region is detected by a current detector using a Hall element.

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: For protection of an output switching transistor used in a pulse signal output circuit, the present invention provides a first detector for detecting over-current flowing through the output switching element, a second detection circuit for producing a detection signal in response to detection of over-current by the first detector in excess of a predetermined rate, and a protection circuit protecting the output switching element by suppressing the current flowing therethrough in response to the detection signal. The protection circuit may suppress the current flowing through the output switching element by both the output of the over-current detector and the detection signal.

Abstract: A circuit interrupter includes a trip unit consisting of a microcomputer and a liquid crystal numeric display mounted on the front panel of the trip unit. A power supply provides operating power for the trip unit even after a tripping operation. A microcomputer includes read-only memory for storing instructions to cause the microcomputer to sequentially display numeric values corresponding to the present electrical conditions through the circuit interrupter and the parameters defining the time-trip characteristic of the interrupter. Storage means are provided to store the level of phase or ground current resulting in a tripping operation and for displaying this value following a trip. Means are also provided for displaying a single digit numeric value indicating the cause of trip.

Abstract: An electrical circuit is provided for actuating the trip mechanism of a circuit interrupter and includes a current sensor having a pair of output terminals and designed to cooperate with at least one electrical power conductor to sense the amount of current flowing in that conductor. The circuit further includes a circuit neutral terminal. A power supply is provided having input terminals with one of the input terminals being connected to one of the output terminals of the current sensor for receiving the sensed current signal therefrom, the other of the input terminals being connected to the circuit neutral terminal. The power supply produces output power at a first voltage level during a first mode of operation of the electrical circuit and produces output power at a second voltage level during a second mode of operation of the electrical circuit, with the second voltage level being substantially higher than the first voltage level.

Abstract: Disclosed is a characteristic timer for a protective relay which provides protection for a portion of an A.C. transmission line. The characteristic timer has digital logic elements adapted to external circuitry for selecting one or more desired phase angles which determines the activation time of a characteristic timer, which, in turn, determines the operational characteristic of the protective relay. The digital logic of the characteristic timer is further adapted to an external circuitry for selecting an integrating or non-integrating type function for the characteristic timer.

Abstract: A method for detecting excessive current in a system and interrupting the delivery of further current thereto comprises determining actual system current, obtaining a value of a predetermined system parameter indicative of the time the actual system current can safely exist in the system, creating a dynamic history of the predetermined system parameter by repetitively modifying the predetermined system parameter in accordance with actual system current, and interrupting power to the system if the dynamic history of the predetermined system parameter exceeds a predetermined threshold. The predetermined system parameter may be quadratically extended into an undefined region in order to decrease the response time to an overload or fault condition.

Abstract: A circuit interrupter includes a microprocessor based trip unit having a plurality of output control lines and a power supply for providing operating power to said trip unit. Interlock means are provided to maintain the output control lines in a predetermined inactive status for a predetermined time period following energization of the power supply to allow time for operating power to rise to a level sufficient to enable the microcomputer to assert positive control over the status of the control lines. An automatic reset circuit is provided to reset the microcomputer program counter to an initialization routine unless a pulse pattern produced by proper execution of the microcomputer instructions is received by the automatic reset circuitry.

Abstract: A control for an AC circuit protection system which is capable of monitoring either single phase or polyphase current flow. The composite current envelope is periodically sampled and the sample values converted into digital form. Succeeding current signals are tested to determine whether they deviate from previous samples by a given amount. Non-deviant samples increment a first counter, while deviant samples increment a second counter. The ratio of the counts is used to recognize current imbalance and control system parameters are adjusted to compensate for the imbalance.

Abstract: A solid state load protection system whereby the current supplied to a load is monitored enabling a test feature to be used. A current sensing function is utilized so as to produce an output current which is proportional to the current in an electrical circuit. Attached to the current sensing function is a load resistor module which converts the current produced by the current sensing function to a voltage which is also proportional to the current utilized by a load. Attached to the module is an overcurrent and timing function and an output function. The overcurrent and timing function monitors the level of voltage from the load resistor module initiating a timeout sequence when the voltage across the load resistor function, which is proportional to the current utilized by the load exceeds a predetermined level for a predetermined period of time thereby initiating a trip signal to the output function which deenergizes the motor by disconnecting it from its source of power.

Abstract: A DC Solid State Overload Relay for use with a DC motor controller is provided with functions to provide instantaneous and delayed tripping of an overload relay by monitoring a standard ammeter shunt signal placed in the power line. The relay circuit uses dropping resistors and a sensing unit with the sensing unit containing separate presetable adjustment for the instantaneous and delayed tripping function and further has automatic reset provisions and a trip indicator which indicates the cause of relay tripping.

Abstract: An overcurrent relay circuit has a power supply developed from a test signal representative of the current in the line being monitored. The power supply is a Zener diode and capacitor arrangement connected in series with the load or test resistor. A variable time-current characteristic circuit (or timing plug) is based upon a variable effective capacitance circuit in which the timing capacitor and resistor currents are isolated from, but dependent upon, one another.

Abstract: A solid state load protection system having an inverse time delay circuit. A current sensing function is utilized so as to produce an output current which is proportional to the current in an electrical circuit. Attached to the current sensing function is a load resistor which converts the current produced by the current sensing function to a voltage which is proportional to the current utilized by the load. Attached to the load resistor is an inverse time delay circuit which serves as an overcurrent and timing function. The overcurrent and timing function monitors the level of voltage from the load resistor initiating a time-out sequence when the voltage across the load resistor, which is proportional to the current utilized by the load, exceeds a predetermined level for a predetermined period of time. The overcurrent and timing function utilizes two diode paths for prohibiting the charging or discharging of a capacitor during a normal or overcurrent condition, respectively.

Abstract: A circuit breaker includes a digital electronic trip unit having a microprocessor. The front panel of the trip unit includes a potentiometer connected across a reference voltage, and a numeric display device. The potentiometer is adjusted by an operator to enter a value of a parameter defining the time-current characteristic of the circuit breaker. An analog-to-digital converter receives the voltage supplied by the potentiometer and converts it to a digital quantity for use by the microcomputer in performing limit checks with the current flow through the contacts of the breaker. The microcomputer formats the converted digital value of the potentiometer voltage and supplies it to a front panel-visible numeric display so that the value of the potentiometer setting as interpreted by the microcomputer in defining the time-current trip characteristic is presented on the numeric display to provide real-time feedback to the operator as he adjusts the parameter value.

Abstract: A circuit breaker, having a latching mechanism and a solenoid senses current through a circuit. The sensed current is converted to a proportional voltage. A current rating plug and receptacle system, responsive thereto, provides a standardized voltage. The proportional voltage is applied across a resistor in series with parallel connected permanent shunt resistor and replaceable plug resistor. The standardized voltage is obtained across the parallel connection. A peak detector provides an approximate true peak value voltage of the standardized voltage. An instantaneous trip circuit, a ground fault detector, and both short term and long term delay circuits provide trip signals upon certain conditions. Upon the presence of any trip signal, an OR circuit provides a control signal to gate an SCR having a thermal switch coupled across its anode and cathode. A supply voltage is applied across a serial connection of the anode, the cathode, and the solenoid.

Abstract: A time relay comprising a device (1) arranged to produce an output (F) having a frequency representative of a parameter (I) to be monitored, a comparator (5) responsive to the output (F) for producing an output (IN) when the value of the monitored parameter exceeds a setting value, and relay operating circuitry for operating the relay when the comparator produces an output for a time determined by the relay characteristic for the value of the monitored parameter. The device is suitably a Carrier Domain Magnetometer (C.D.M.) and the operating circuitry suitably includes a digitally addressable memory (8) in which the relay characteristic is stored.

Abstract: A timing circuit for use in an overcurrent relay is disclosed. A plurality of non-interacting R-C circuits whose outputs are summed is provided. The signal representing the summed outputs of the R-C circuits represents one term of the inverse time-current relation it is desired to emulate. Each time the summed signal reaches a predetermined level, a pulse is generated. The frequency of the pulses determines the length of a time delay before the protected circuit is interrupted. When it is necessary to take the second term of the time-current relation into account, this can be done by providing a multivibrator that emits pulses of an adjustable duration responsive to the summed signal and that itself triggers the generation of the pulse train constituting the timing circuit output.

Abstract: An overcurrent signal is replicated by current mirrors for joint processing by a long-time trip mode network and a short-time trip mode network pursuant to initiating a circuit breaker trip function after an adjustably predetermined delay predicated on the overcurrent signal magnitude. The former network measures signal against a sloping I.sup.2 t portion of an established trip time curve, while the latter optionally measures the overcurrent signal against a second I.sup.2 t curve portion terminating in a selected one of plural fixed time delay curve portion. Short-time delay zone selective interlocking between upstream and downstream breakers and long-time delay pickup indication are also disclosed.

Abstract: An electrical device for protecting an alternating current network in which a static inverse time-overcurrent relay obtains network current information and relay circuit operating power from a current transformer having two secondary windings. Low transformer burden and accurate network information signals that are linearly responsive to a wide range of network current magnitudes are achieved through the use of a switching circuit that prevents the simultaneous operation of both secondary windings. The relay circuit employs an RC network with a short, precision time constant for curve shaping and employs digital counting techniques to provide time delay multiplication, precision time scale selection and a variable delay time variable in accordance with the magnitude of system current.

Abstract: A method of and a protection relay for protecting electrical equipment. The method includes dividing a predetermined dividend value by a signal corresponding to the load current in the equipment to provide a quotient signal, and then linearly integrating the quotient signal. When the integrated signal reaches a predetermined value, the equipment is tripped. This provides an overload vs tripping time characteristic which is substantially linear. The method further provides for sensing whether the equipment is operating in a start up mode or in a normal running mode, and then automatically to select a less sensitive overload vs tripping time characteristic when the equipment operates in the start up mode and automatically to switch to a more sensitive characteristic when the equipment reverts to its normal running mode.

Abstract: A monolithic solid state power controller generally comprises a power supply, zero voltage crossing detector, operator interface circuitry, current sensing and trip timing logic (having zero current detection capability), drive circuitry, and a power switch. The current sensing and trip timing logic functions are implemented in a monolithic device which provides flexible mode of operation of the switch, operator command validation, status and mode indication, drive enablement in synchronization with zero voltage crossing of the source voltage, and tripout operation in synchronization with zero current crossing in the load current. Both fast trip (in response to catastrophic overcurrent) and timed trip (in response to overcurrent conditions occurring over a period of time) capabilities are provided.

Abstract: A power transistor in the final stage of an IC amplifier feeding a reactive load, such as a loudspeaker, has an emitter resistor connected across the input of a monitoring transistor by way of a diode, the monitoring transistor being part of a protective circuit which reduces the input signal to the power amplifier in the event of an overload. To retard the response of the protective circuit, for the purpose of preventing signal distortions in the event of brief power surges, the diode and the monitoring transistor are so disposed on the silicon chip of the amplifier that a thermal wave from the overheating power transistor will first strike the diode, thereby reducing its resistance to compensate for an increased voltage drop across the emitter resistor, and will reach the monitoring transistor with a certain delay; if the overload persists, the resulting increase in the conductivity of the monitoring transistor re-establishes the full sensitivity of the protective circuit.

Abstract: A bridge circuit including an eight-leg full wave rectifier bridge connected to rectify the phase and neutral currents produced by three wye-connected current transformers magnetically coupled to respective phases of a three-phase electric power circuit, and used with one or more resistive elements to provide instantaneous D.C. voltage outputs at least once every current cycle, proportional to the highest and/or lowest peak phase current and to the peak neutral or ground current of the power circuit, for operating or preventing the operation of a circuit interrupter in the power circuit being measured.

Abstract: Separate current transformers sense the individual currents flowing in each conductor of a distribution circuit. A full wave rectifying network includes a plurality of parallel pairs of like poled, series diodes connected between a pair of buses. One corresponding side of each transformer secondary is connected to the junction between a different diode pair. A series circuit consisting of an additional pair of like poled diodes and a burden resistor is also connected between the buses. The corresponding other sides of the transformer secondaries are connected in common to the junction between the additional diode pair. A voltage is developed across the burden resistor only upon the existence of an imbalance in the currents flowing in the distribution circuit.

Abstract: A device for detecting a persisting electrical overload in an electrical system includes means for monitoring an electrical parameter in the electrical system and for generating an electrical signal whose magnitude represents the instantaneous absolute value of the parameter, reference means which generates an output signal of predetermined value and which develops, in cooperation with the monitoring means, an electrical signal whose magnitude represents the amount by which the magnitude of the absolute value signal exceeds the predetermined value, integrator means to integrate the aforementioned electrical signal and to generate an output whose magnitude includes a component representative of the product of the electrical signal and a time-increasing value that represents the duration that an overload has persisted; and comparator means to continuously compare the magnitude of the integrator output signal with a second preselected value and which generates an indicative output whenever the integrator output