Apparatus, system and method for monitoring an industrial plant or an industrial machine

Abstract

To provide a safety device capable of monitoring whether or not an electric motor is actually stopped when the electric motor is not energized, monitoring whether or not a load moved by the electric motor is stopped, and being compact and easily installed.SOLUTION: A safety device (10) for monitoring an industrial machine or an industrial plant (100) having an electric motor (101). The safety device (10) comprises a detection unit for detecting at least a first physical quantity relating to the operation of the electric motor (101) and a second physical quantity relating to the movement of the load (105), and a signaling unit configured to transmit a safety signal generated by a processing unit. The processing unit is configured to compare at least two physical quantities with each other in order to detect a failure or an anomaly and to generate a safety signal based on the comparison.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a safety device, a safety system and related processes for monitoring an industrial machine or plant that includes an electric motor connected to a load to be moved.

[0002] The devices, systems and processes according to the present invention find application, for example, in industrial machines or industrial plants where it is necessary to monitor electric motors and their loads to determine whether the machine or plant is in a safe state. [Background technology]

[0003] There are known industrial applications in machines and plants where the speed of electric motors needs to be monitored.

[0004] A first example is monitoring the speed of an electric motor to determine if the electric motor is stopped, i.e., the speed is zero, thereby allowing or denying a user access to a hazardous area where the electric motor or the load it is moving is present.

[0005] This case is typical in automatic or semi-automatic machines, such as band saws, circular saws, etc. In band saws and circular saws, an electric motor is used to move a load (i.e. a circular or band saw blade) that has a large inertia and may remain in motion for some time after the electric motor has stopped.

[0006] To determine whether an electric motor is stopped, i.e., has zero speed, it is known to use a safety device such as that described in U.S. Pat. No. 6,049,284 which involves measuring the voltage between steps of the electric motor when the electric motor is de-energized and comparing the measured voltage to a reference voltage.

[0007] If the measured voltage is lower than the reference voltage, the electric motor is considered to be stopped and the safety device signals that the machine is in a safe state.

[0008] Although such prior art devices are well-regarded and widely used, they suffer from several drawbacks.

[0009] Such known devices have the disadvantage that they may signal that the electric motor is stopped even when the load is still moving. This may result in the known devices allowing access to the machine even when the load is known to be moving. Indeed, in many applications, the load is not directly connected to the shaft of the electric motor being monitored, but is instead connected by a transmission such as a belt, chain, etc. In the event of a failure of such a transmission, the known devices will continue to allow access to the danger zone in which the electric motor is located together with the load, even when the electric motor is stopped, in case there is a risk that the load is still moving.

[0010] This drawback can allow access to dangerous areas of the machine even when the load is not completely stopped, creating a dangerous situation for the operator.

[0011] Relevant prior art includes patent document DE4331741C2.

[0012] It is therefore one object of the present invention to provide a safety device that is compact and easy to install, which makes it possible to both monitor whether an electric motor is actually stopped when not energized, and to monitor whether a load being moved by the electric motor is stopped.

[0013] Another object of the present invention is to provide a safety device and procedure for improving the safety of a machine or system that includes at least one electric motor. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic diagram of an industrial machine or plant associated with a safety device according to the present invention; [Figure 2] 1 is a schematic diagram of a safety device according to each embodiment of the present invention. [Figure 3] 1 is a schematic diagram of a safety device according to each embodiment of the present invention. [Figure 4] 1 is a schematic diagram of a safety device according to each embodiment of the present invention. [Figure 5] 1 is a schematic diagram of a safety device according to each embodiment of the present invention. [Figure 6] 1 is a schematic diagram of a safety device according to each embodiment of the present invention. [Figure 7] 1 is a schematic diagram of a portion of a safety device according to embodiments of the present invention; [Figure 8] FIG. 2 is a block diagram of a process according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] With reference to FIG. 1 , a safety device 10 according to the present invention is configured to be associated with an industrial machine or system 100 comprising at least one electric motor 101 powered by a power supply network 102 and connected to a load 105 located in a hazardous area 106 of the industrial machine or system 100.

[0016] The load 105 may be any machine, such as a circular saw, a band saw, a robotic arm, a grinding wheel, etc., that is driven by an electric motor 101, either directly or by any kind of transmission member 104, such as gears, rack and pinion, chains, belts, ropes, springs, clutches, elastic couplings, viscous couplings, universal joints, crank connecting rod mechanisms, oscillating glyphs, cam or template mechanisms, etc.

[0017] The device 10 is configured to transmit a safety signal S relating to the safety of the machine or industrial plant 100 for activating a safety function of the machine or industrial plant 100 .

[0018] The device 10 is connected to a controller 110, such as a PLC, of ​​a machine or industrial plant 100 and is able to send a safety signal S to the latter.

[0019] As an example, the safety signal S may enable or prohibit operation of the machine or industrial plant 100. Alternatively, the safety signal S may allow or prohibit operator access to the hazardous area 106 in which the load 105 is located.

[0020] The device 10 of the invention is configured to compare a first physical quantity related to the operation of the electric motor 101 and a second physical quantity related to the state of the load 105 with each other.

[0021] The first physical quantity is selected from the voltage, frequency, or both measured on the power line 102 of the electric motor 101 .

[0022] The second physical quantity is selected from the speed, motion, motion state, position of the load 105, and any other physical quantity related to the state of the load 105, such as temperature, pressure, torque, etc.

[0023] It should be noted that, below and in the claims, when reference is made to the speed, movement, or position of the load 105, this also refers to the speed or position of one or more transmission mechanisms 104 interposed between the electric motor 101 and the load 105.

[0024] It should be noted that, below and in the claims, when reference is made to the speed, movement, or position of the load 105, this also refers to the speed or position of one or more motion transmission members 104 interposed between the electric motor 101 and the load 105.

[0025] The comparison is made to detect a fault or abnormal condition related to the movement of the load 105 or the transmission member 104 and to activate a safety function of the machine or industrial plant 100 if a fault or abnormal condition is detected.

[0026] In a first form of implementation, the first physical quantity is a voltage measured on the power supply line 102, and the second physical quantity is a physical quantity related to the operating state of the load 105. For example, the second physical quantity is the speed of the load 105.

[0027] In this case, if the speed of the load 105 is greater than zero or greater than a minimum threshold and the voltage of the power supply 100 is zero or less than a minimum threshold corresponding to a stalled electric motor 101 situation, a fault is presumed.

[0028] In this case, the device 10 sends a safety signal S to prohibit or keep prohibited access to the danger zone 106 in which the load 105 is located, or sends a signal to stop the industrial machine or industrial plant 100.

[0029] Such a safety signal S may be sent to a controller 110 which in turn issues a command to an interlock 111 associated with access to the hazardous area 106, or may be sent directly to an interlock 111 or other general monitoring system of the plant of which the machine is a part.

[0030] In other words, the device 10 is configured to allow access to the danger zone 106 only if the electric motor 101 and the load 105 are simultaneously stopped.

[0031] Advantageously, the device 10 of the present invention prohibits or keeps prohibited access to the danger zone 106 in which the load 105 is located, even if zero voltage is detected on the power supply line 102, which corresponds to a situation in which the electric motor 101 is stopped, even though the load 105 is still moving. In this way, the device 10 can prohibit or keep prohibited access to the danger zone 106 even in the event of a failure of the motion transmitting member 104, thereby improving the safety of the industrial machine or industrial plant 100.

[0032] In another embodiment, the first physical quantity is a frequency measured on the power line 102 and the second physical quantity is a speed of the load 105 .

[0033] In this case, the comparison is made to detect an abnormal situation of either blocking, slipping, or partial damage of the motion transmission member 104. In this case, if the speed of the load 105 is zero while the frequency of the power supply 102 is greater than zero, a failure of the motion transmission member 104 or a blockage of the load 105 is inferred.

[0034] Alternatively or additionally, a comparison is made to verify that the relationship between the speed of the load 105 and the frequency detected on the power line 102 of the electric motor 101 meets predetermined parameters.

[0035] For example, the speed of the load 105 may be proportional to the frequency detected on the supply line 102 of the electric motor 101 .

[0036] Alternatively, the relationship between the speed of the load 105 and the frequency detected on the supply line 102 of the electric motor 101 may be defined by one or more predetermined mathematical functions of any type and stored by the device 10.

[0037] In this case, if a relationship is detected between the speed of the load 105 and the frequency sensed on the power line 102 that does not correspond to a predetermined parameter, a fault is presumed, or, for example, excessive wear of the motion transmitting member 104 or excessive force applied to the load 105. In such a case, the device 10 transmits a safety signal S to inhibit the supply of power to the electric motor 101 if a fault or abnormal situation is presumed.

[0038] Such a safety signal S is sent to a controller 110 which controls a contactor 112 associated with the power line 102 or can send the safety signal to the contactor 112 directly.

[0039] The device 10 of the present invention can inhibit the supply of power to the electric motor 101 even when the electric motor 101 appears to be operating normally despite a fault downstream of the electric motor 101, for example in the load 105 or the motion transmitting member 104. Also, based on set parameters, excessive wear of the motion transmitting member 104 can be inferred, and for example a safe signal S or an unsafe signal can be sent from the device 10 to the controller 110 to indicate the need for maintenance on the machine 100.

[0040] 2 to 6, the device 10 comprises a detection unit 11 configured to detect first and second physical quantities, a processing unit 12 configured to compare the first and second physical quantities and process a safety signal S, and a signaling unit 13 configured to transmit the safety signal S in a fail-safe manner.

[0041] The signalling unit 13 may include fail-safe switching means 45, 46 or a digital output, as explained below.

[0042] The detection unit 11 is connected to the power supply line 102 of the electric motor 101 for detecting a first physical quantity related to the operation of the electric motor 101, and is connected to a sensor 107 configured to detect a second physical quantity related to the movement of the load 105.

[0043] The detection unit 11 comprises a first input channel 16 configured to be connected to a power supply line 102 of the electric motor 101 for detecting a first physical quantity related to the operation of the electric motor 101 .

[0044] In particular, the first input channel 16 is configured to sense the voltage of the power supply 100 and to send a motor signal M related to a first physical quantity to the processing unit 12 .

[0045] The motor signal M may encode the absolute value of the detected voltage (peak or peak-to-peak value) and / or the frequency value of the alternating current (AC) voltage detected on the power line 102, or the value of the current drawn by the electric motor 101.

[0046] For example, if the power line 102 of the electric motor 101 is three-stage, the first input channel 16 may be connected in use to two of the three stages L1, L2, L3 of the power line 102.

[0047] The device 10 also comprises a second input channel 36 connected to the processing unit 11 and configured to be connected to a sensor 107 suitable for being associated with the load 105 and / or the motion transmitting member 104 interposed between the load 105 and the electric motor 101. The second input channel 36 is configured to detect a second physical quantity via the sensor 107.

[0048] The sensor 107 is positioned between the load 105 and a motion transmission member 104 interposed between the electric motor 101 and the load 105, and is configured to calculate, or have the processing unit 11 calculate, the speed of the load 105, the rotational speed of the load 105, or other physical quantity.

[0049] For example, the sensor 107 is configured to detect the change in position or velocity of the load 105 over time and send to the processing unit 11 a signal L relating to a second physical quantity, hereinafter referred to as load signal L.

[0050] The load signal L may include information about the movement state of the load 105, the actual speed of the load 105, or the change in the position of the load 105 over time.

[0051] To illustrate this, the sensor 107 may be an inductive rotation sensor, a generator, an encoder, a pressure sensor, a temperature sensor, a torque sensor, or any other physical quantity.

[0052] With respect to the embodiment of FIG. 6 , the sensing unit 11 may further include a third input channel 16′ configured to be connected to the power supply line 102 of the electric motor 101 to detect a first physical quantity related to the operation of the electric motor 101.

[0053] In particular, the third input channel 16' is configured to sense the voltage on the power line 102 and to transmit a second motor signal M' to the processing unit 12 that correlates to the sensed voltage.

[0054] The second motor signal M' may encode the absolute value of the sensed voltage and / or the frequency value of the sensed alternating current (AC) voltage on the power line 102 and / or the value of the drawn current.

[0055] Preferably, and with reference to FIG. 7, the first input channel 16 and the third input channel 16' are substantially identical and each comprise an amplification means 18 and a measurement unit 19.

[0056] The amplifier means 18 is connected to the power supply line 102 and is configured to scale the detected voltage in order to transmit to the measurement unit 19 at least one intermediate voltage signal IV having a voltage value lower than the sensed voltage.

[0057] In this specification and the appended claims, the term "amplified" also includes cases where a signal is attenuated by being amplified by a value of 1 or less.

[0058] In the example shown here, the intermediate voltage signal IV is a square wave related to the time course of the measured voltage between two steps L1, L2, L3 of the power line 102 of the electric motor 101.

[0059] By way of example, the amplifying means 18 include a differential amplifier, which is known per se and will not be described in detail.

[0060] The amplifier means 18 are also connected to a measurement unit 19 by a frequency line 20 and a voltage line 21 .

[0061] The frequency line 20 advantageously comprises a filter circuit 22 arranged to supply the measurement unit 19 with an intermediate IF frequency signal which has been noise filtered and has a maximum acceptable value for the measurement unit 19. The filter circuit 22 comprises, arranged in series, a first-order filter 23, a comparator with hysteresis 24 and a voltage divider 25, all of known type and will not be described in detail.

[0062] The voltage line 21 includes an attenuation circuit 26 configured to provide the measurement unit 19 with an intermediate voltage IV signal having a maximum allowable value for the measurement unit 19. In particular, the attenuation circuit 26 includes a known voltage divider 27, which will not be described in detail.

[0063] The measurement unit 19 is configured to sample the intermediate frequency signal IF and the intermediate voltage signal IV. Furthermore, the measurement unit 19 is configured to obtain frequency information of the electric motor 101 by performing a measurement of the intermediate frequency signal IF. In this case, this measurement includes measuring the period of the intermediate frequency signal IF and therefore its frequency.

[0064] In this specification and the appended claims, the term "frequency" is defined to mean a quantity related to the rotational speed of the electric motor 101.

[0065] Furthermore, the first measuring unit 19 is configured to obtain voltage information relating to the measurable voltage on the power supply line 102 by performing measurements on the intermediate voltage signal IV.

[0066] In this case, the measuring unit 19 measures the voltage of the intermediate voltage signal IV instantaneously, the measured value corresponding to the voltage information.

[0067] The measurement unit 19 is configured to transmit said motor signals M, M', including said frequency information and / or said voltage information, to the processing unit 12, preferably in a digital format corresponding to said first physical quantity.

[0068] Preferably, the processing unit 12 comprises a first arithmetic unit 41 and a second arithmetic unit 42 which are redundantly separated and connected to each other.

[0069] Each of the calculation units 41, 42 is configured to perform a comparison between a first physical quantity and a second physical quantity.

[0070] In one embodiment, each calculation unit 41, 42 is configured to compare voltage information contained in the motor signal M with the speed of the load 105 detected via the load signal L. In this case, each calculation unit 41, 42 performs the comparison to verify that if the voltage information corresponds to a stopped state of the electric motor 101, the speed of the load 105 is also zero.

[0071] If this condition is not verified, the processing unit 12 is configured to generate a safety signal S for activating a safety function of the machine or industrial plant 100 .

[0072] In this case, the switching means 45, 46 can be controlled to switch from an activated state to an off state or vice versa to generate a safety signal S. Alternatively, the safety signal S can be transmitted in digital form via a digital output to an external user to notify them of the fault condition.

[0073] Advantageously, in this way, if the electric motor 101 stops while the load 105 is moving, for example due to a failure of the motion transmission member 104, the safety signal S can be used to activate a safety function of the machine or industrial plant.

[0074] For example, in this case the activated safety function may be the prohibition of access to a dangerous area 106 of the machine or industrial plant 100 and / or the reporting of a fault.

[0075] In a further embodiment, each computing unit 41, 42 is configured to compare frequency information contained in said motor signal M with the speed of said load 105 obtained from said load signal L.

[0076] In this case, the comparison is made to detect abnormal conditions such as blocking, slipping, or damage to the motion transmitting member 104 .

[0077] Each computing unit 41, 42 generates a safety signal S for activating a safety function of the machine or industrial plant 100 when it detects that the frequency of the power line 102 is greater than zero and the rotational speed of the load 105 is zero.

[0078] Instead, when each computing unit 41, 42 detects that the frequency of the power line 102 corresponds to a speed greater than or less than the rotational speed of the load 105, it generates a safety signal S indicating a slip condition.

[0079] Alternatively, if each of the computing units 41, 42 detects that the correspondence between the frequency on the power line 102 and the rotational speed of the load 105 does not conform to a predetermined parameter, e.g., a mathematical function stored in the computing unit 41, 42, it generates a safety signal S indicating an abnormality. In this case, the safety signal S can be generated by controlling the switching means 45, 46 to switch from an active state to an inactive state or vice versa. Alternatively, the safety signal S can be transmitted digitally to an external user via an auxiliary digital output, and the degree of the detected abnormality can also be signaled. For example, in the embodiment shown in FIG. 2, the first computing unit 41 is connected to the first input channel 16, and the second computing unit 42 is connected to the second input channel 36. In this case, the first computing unit 41 transmits a motor signal M to the second computing unit 42, and the second computing unit 42 transmits a load signal L to the first computing unit 41. In another embodiment, for example as shown in FIG. 3, a first arithmetic unit 41 and a second arithmetic unit 42 are connected to the first input channel 16 and the second input channel 36 .

[0080] In this case, the first arithmetic unit 41 transmits the result of its comparison to the second arithmetic unit 42 , and the second arithmetic unit 42 transmits the result of its comparison to the first arithmetic unit 41 .

[0081] Furthermore, each computing unit 41, 42 is configured to verify that the result of its own comparison matches the result of the comparison made by the other computing unit 41, 42 and to generate a safety signal S. In another possible embodiment, the computing unit 41 is connected to both input channels 16, 36, while the second computing unit 42 is connected only to either the first or the second input channel 16, 36.

[0082] For example, in the embodiment of FIG. 5, a first arithmetic unit 41 is connected to the first input channel 16 and a second arithmetic unit 42 is connected to the first input channel 16 and the second input channel 36 .

[0083] In this case, the second arithmetic unit 42 sends the load signal L to the first arithmetic unit 41 .

[0084] Again, the first computing unit 41 transmits the result of its comparison to the second computing unit 42, and the second computing unit 42 transmits the result of its comparison to the first computing unit 41. Furthermore, each computing unit 41, 42 is configured to verify that the result of its comparison matches the result of the comparison made by the other computing unit 41, 42 and to generate a safety signal S.

[0085] Alternatively, in the embodiment shown schematically in FIG. 4, the first arithmetic unit 41 is connected to the first input channel 16 and the second input channel 36, and the second arithmetic unit 42 is connected to the second input channel 36.

[0086] In this case, the first arithmetic unit 41 sends the motor signal M to the second arithmetic unit 42 .

[0087] Again, the first computing unit 41 transmits the result of its comparison to the second computing unit 42, and the second computing unit 42 transmits the result of its comparison to the first computing unit 41. Furthermore, each computing unit 41, 42 is configured to verify that the result of its comparison matches the result of the comparison made by the other computing unit 41, 42 and to generate a safety signal S.

[0088] In a further embodiment shown in Figure 6, a first calculation unit 41 is connected to the first input channel 16 and the second input channel 36, and a second calculation unit 42 is connected to the second input channel 36 and the third input channel 16'.

[0089] In this case, the first calculation unit 41 is configured to compare a first physical quantity contained in the motor signal M with a second physical quantity contained in the load signal L, and the second calculation unit 42 is configured to compare a first physical quantity contained in the second motor signal M' with a second physical quantity contained in the load signal L.

[0090] Again, the first computing unit 41 transmits the result of its comparison to the second computing unit 42, and the second computing unit 42 transmits the result of its comparison to the first computing unit 41. Furthermore, each computing unit 41, 42 is configured to verify that the result of its comparison matches the result of the comparison made by the other computing unit 41, 42 and to generate a safety signal S.

[0091] In another embodiment not shown, the first arithmetic unit 41 is connected to the first input channel 16, the second arithmetic unit 42 is connected to the third input channel 16', and one of the first arithmetic unit 41 and the second arithmetic unit 42 is connected to the second input channel 36 and transmits the load signal L to the other arithmetic unit 41, 42.

[0092] The signalling unit 13 is controlled by the processing unit 12 and comprises switching means 45, 46 suitable for switching from an activated state to an inactivated state and vice versa, in which case the safety signal S corresponds to the state of the switching means 45, 46, i.e. activated or inactivated.

[0093] For example, a safety signal S activating a safety function of the machine or industrial plant 100 that allows access to personnel within the danger zone 106 may correspond to the activation state of the switching means 45 , 46 .

[0094] Alternatively, the safety signal S which activates a safety function of the machine or industrial plant 100 which inhibits the supply of power to the electric motor 101 may correspond to the inactivation of the switching means 45, 46.

[0095] In another embodiment, the signaling unit 13 comprises a digital output (not shown) connected to the processing unit 12 and configured to enable transmission to an external user of a signal in digital form generated by the processing unit 12. In this case, the safety signal S corresponds to the digital signal generated by the processing unit 12.

[0096] For example, the digital output may comprise a USB type connector, preferably a USB-C type connector, connected to the processing unit 12. Alternatively or additionally, the digital output may comprise an industrial fieldbus or communication bus, such as an IO-Link bus, connected to the processing unit 12.

[0097] The first and second computing units 41, 42 are configured to control the signaling unit 13 based on a comparison of the first and second physical quantities.

[0098] For example, the signaling unit 13 may include a first Output Signal Switching Device (OSSD) type safety output section 45 connected to the first arithmetic unit 41 and a second OSSD type safety output section 46 connected to the second arithmetic unit 42.

[0099] The first safety output unit 45 and the second safety output unit 46 may be independent of each other, or may be connected in series.

[0100] The detection unit 11 and the processing unit 12 are preferably, but not necessarily, obtained on a single printed circuit board and separated from each other by an insulating barrier (not shown). Advantageously, the insulating barrier provides electrical isolation between the detection unit 11 and the processing unit 12. This makes it possible to avoid malfunctions or failures of the processing unit 12 due to high voltages present in the detection unit 11, particularly in the first and third input channels 16, 16′, and consequently improves the safety of the device 10 of the present invention.

[0101] For example, the isolation barrier may comprise one or more optocouplers, or optical isolators, disposed between at least one input channel 16 , 36 , 16 ′ and the processing unit 12 .

[0102] The invention relates to a safety system comprising an electric motor 101 connected to an electric power line 102 and connected to a load 105. The safety system comprises a safety device 10 and a sensor 107 as described above.

[0103] Preferably, the system comprises a controller 110, for example a PLC, connected to the device 10, receiving the safety signals S and activating the safety functions of the machine in response to the control signals.

[0104] More specifically, the controller 110 controls an inverter (not shown in FIG. 1) that controls the electric motor 101, and the safety device 10 communicates with the controller 110 and also directly controls two contactors (also not shown) located upstream or downstream of the inverter to cut off the power supply to the electric motor 101 in an unsafe situation.

[0105] Alternatively, the device 10 sends a safety signal S to prevent access to the danger zone 106 when the load 105 is moving.

[0106] The invention also relates to a safety procedure for an industrial machine or plant, comprising a detection step S1 of detecting a first physical quantity related to the operation of the electric motor 101 and a second physical quantity related to the state of the load 105 .

[0107] Here and hereinafter, the state of the load 105 refers to the movement of the load 105, including, for example, a state in which the load 105 is stationary.

[0108] In the detection step S1, the detection unit 11 detects the voltage of the power line 102 of the electric motor 101 and transmits at least a motor signal M correlating with a first physical quantity corresponding to the detected voltage to the processing unit 12. Further in the detection step S1, the detection unit 11 detects a change in the speed or position of the load 105 via the sensor 107 and transmits a load signal L correlating with the state of the load 105 corresponding to a second physical quantity to the processing unit 12.

[0109] The processing step S3 also includes the processing unit 12 comparing the first physical quantity with the second physical quantity and generating a safety signal S in response to the comparison.

[0110] In step S1, the first input channel 16 detects the voltage on the power line 102 of the electric motor 101, while in a subsequent preparation step S2, the first input channel 16 processes the voltage or frequency detected on the power line 102 and sends at least one motor signal M to the processing unit 12.

[0111] Further, the detection step S1 provides that the sensor 107 detects a second physical quantity related to the state and / or movement of the load 105, and the preparation step S2 provides that the sensor 107 generates and transmits a load signal L to the processing unit 12.

[0112] Optionally, in addition to the first input channel 16, a third input channel 16' can also be connected to the power supply line 102 of the electric motor 101 for transmitting respective motor signals M, M' to respective arithmetic units 41, 42 included in the processing unit 12.

[0113] Furthermore, the sensor 107 is configured to be connected to the second input channel 36 for transmitting the load signal L to the respective computing unit 41, 42.

[0114] It should be noted that for the transmission of the motor signals M, M', the preparation step S2 may include an amplification substep S2.1 in which the amplification means 18 scales the detected voltage and transmits to each measurement unit 19 at least one respective intermediate voltage signal IV having a value lower than the detected value.

[0115] Furthermore, the preparation step S2 may also include a filtering substep S2.2 in which each intermediate signal I is filtered by a respective filter circuit 22 to provide a respective intermediate frequency signal IF to each measurement unit 19. The preparation step S2 may also include an attenuation substep S2.3 in which each intermediate signal I is attenuated by a respective attenuation circuit 26 to provide a respective intermediate voltage signal IV, IV' to each measurement unit 19.

[0116] The preparation step S2 includes a measurement substep S2.4 in which each measurement unit 19 measures the respective intermediate frequency signal IF and intermediate voltage signal IV to derive frequency information and voltage information. Furthermore, in the measurement substep S2.4, the measurement unit 19 transmits the motor signals M, M' including the respective frequency information and voltage information to the respective calculation units 41, 42 of the processing unit 12.

[0117] Advantageously, the present invention relates to a safety system for monitoring an industrial machine having an electric motor connected by a transmission to a load located in a danger area of ​​the industrial machine, and to a safety device for monitoring the industrial machine.

[0118] Such a device may comprise or include all of the features previously described.

[0119] From the above description, the features and advantages of the safety device and process for monitoring electric motors that are the subject of the present invention are apparent.

[0120] The present invention thus conceived can be modified and changed in various ways within the scope of protection of the invention as defined in the accompanying claims.

[0121] Moreover, all the details may be substituted with other technically equivalent elements. In practice, the materials used, as well as the accompanying shapes and dimensions, may be modified according to the attendant needs and the current state of the art.

[0122] Where reference numbers are used to designate structural features and techniques referred to in the following claims, these reference numbers are used solely to facilitate understanding of the claims and, therefore, do not constitute any limitation on the interpretation of each identified element.

Claims

1. A safety device (10) for monitoring an industrial machine (100) having an electric motor (101) connected via a motion transmission member (104) to a load (105) located in a danger area (106) of the industrial machine (100), comprising: a detection unit (11) configured to detect both a first physical quantity related to the operation of the electric motor (101) and a second physical quantity related to the state of the load (105); at least one processing unit (12) configured to compare the first physical quantity with the second physical quantity to detect a fault or anomaly and to generate a safety signal (S) based on the comparison; a signaling unit (13) configured to reliably transmit the safety signal (S) to activate or deactivate a safety function of the industrial machine (100), The first physical quantity is selected from a voltage, a frequency, a current, and a combination thereof measured in a power supply line (102) of the electric motor (101), and the second physical quantity is selected from a speed, a position, and a combination thereof of the load (105) or the motion transmission member (104) interposed between the load (105) and the electric motor (101). Safety device (10).

2. The detection unit (1) a first input channel (16) connected to the power supply line (102) of the electric motor (101) for detecting a voltage on the power supply line (102) and configured to transmit at least a motor signal (M) correlated to the detected voltage to the processing unit (12); a second input channel (36) connected to a sensor (107) associated with the load (105) for detecting the second physical quantity and configured to transmit at least one load signal (L) correlated to the second physical quantity to the processing unit (12); A safety device (10) according to claim 1.

3. the signaling unit (13) comprises switching means (45, 46) controlled by the processing unit (12); 3. A safety device according to claim 1 or 2.

4. The processing unit (12) has a pair of arithmetic units (41, 42) redundantly connected to each other, and each of the pair of arithmetic units is configured to compare the first physical quantity with the second physical quantity to generate the safety signal (S). A safety device according to any one of claims 1 to 3.

5. The safety feature is prohibiting or keeping prohibited access to said danger zone (106); Disabling the supply of power to the electric motor (101); generating a stop command for the industrial machine (100); and / or inhibiting the industrial machine from starting. A safety device according to any one of claims 1 to 4.

6. an electric motor (101); a power supply line (102) for the electric motor (101); a load (105) moved by said electric motor (101); A device (10) according to any one of claims 1 to 5, a sensor (107) connected to the device (10) and associated with the load (105) for detecting a speed, a position, or other physical quantity of the load (105); A safety system comprising:

7. A safety process for an industrial machine comprising an electric motor (101) connected to a load (105) via a motion transmission member (104) and supplied by a power supply line (102), said safety process comprising at least the following steps: a detection step (S1) of detecting a first physical quantity related to the operation of the electric motor (101) and a second physical quantity related to the movement of the load (105); a processing step (S3) of comparing the first physical quantity with the second physical quantity to detect a fault or abnormality, and generating a safety signal (S) based on the comparison to activate a safety function of the industrial machine (100). Safety process.

8. The safety function prohibits or keeps prohibited access to the danger zone (106), prohibits the supply of power to the electric motor (101), generates a stop command for the industrial machine (100) and / or prohibits the start of the industrial machine (100).

8. The safety process of claim 7.

9. The first physical quantity is selected from the voltage and frequency measured in the power supply line (102) of the electric motor (101), and the second physical quantity is selected from the speed and position of the load (105) or the motion transmission member (104) interposed between the load (105) and the electric motor (101).

9. A safety process according to claim 7 or 8.

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