CN113933705B - System for monitoring an electric motor - Google Patents
System for monitoring an electric motor Download PDFInfo
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- CN113933705B CN113933705B CN202111127882.4A CN202111127882A CN113933705B CN 113933705 B CN113933705 B CN 113933705B CN 202111127882 A CN202111127882 A CN 202111127882A CN 113933705 B CN113933705 B CN 113933705B
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- 238000012544 monitoring process Methods 0.000 title claims abstract description 56
- 230000004044 response Effects 0.000 claims abstract description 117
- 230000000670 limiting effect Effects 0.000 claims description 47
- 238000010586 diagram Methods 0.000 description 9
- 238000004519 manufacturing process Methods 0.000 description 8
- 238000005259 measurement Methods 0.000 description 5
- 238000004364 calculation method Methods 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 238000013459 approach Methods 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000010276 construction Methods 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000001976 improved effect Effects 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
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- 238000012360 testing method Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/34—Testing dynamo-electric machines
- G01R31/343—Testing dynamo-electric machines in operation
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B19/00—Programme-control systems
- G05B19/02—Programme-control systems electric
- G05B19/418—Total factory control, i.e. centrally controlling a plurality of machines, e.g. direct or distributed numerical control [DNC], flexible manufacturing systems [FMS], integrated manufacturing systems [IMS] or computer integrated manufacturing [CIM]
- G05B19/4183—Total factory control, i.e. centrally controlling a plurality of machines, e.g. direct or distributed numerical control [DNC], flexible manufacturing systems [FMS], integrated manufacturing systems [IMS] or computer integrated manufacturing [CIM] characterised by data acquisition, e.g. workpiece identification
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P90/00—Enabling technologies with a potential contribution to greenhouse gas [GHG] emissions mitigation
- Y02P90/02—Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]
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- Automation & Control Theory (AREA)
- Control Of Electric Motors In General (AREA)
Abstract
The present invention provides a system for monitoring an electric motor, characterized in that the system for monitoring an electric motor comprises: the distributed control system analog input clamping piece, the current value adjusting unit and the monitoring unit; the current value adjusting unit is connected between the analog quantity input clamping piece of the distributed control system and the external transmitter, so that response current generated by the external transmitter based on working current of the motor is received, when the current value of the response current is larger than an alarm current value for triggering alarm of the analog quantity input clamping piece of the distributed control system, the current value of the response current is adjusted to be smaller than the alarm current value, and the response current is provided for the analog quantity input clamping piece of the distributed control system; the distributed control system analog input card is connected with the monitoring unit so as to supply the response current received from the current value adjusting unit to the monitoring unit, so that the monitoring unit monitors the operating state of the motor based on the response current.
Description
Technical Field
Embodiments of the present description relate to the field of industry and, in particular, to a system for monitoring an electric motor.
Background
The distributed control system (Distributed Control System, DCS) adopts the basic design concept of control distribution, operation and management concentration, so that the distributed control system has the advantages of strong universality, flexible system configuration, perfect control function and the like, and is widely applied to various production processes at present.
For example, in a power plant production environment, a DCS may monitor and/or control various devices associated with a power generation production process. For example, the DCS can monitor the operating state of the motor via a transmitter to control and manage the motor accordingly. How to efficiently monitor the motor becomes one of the problems to be solved.
Disclosure of Invention
In view of the above-described problems of the prior art, embodiments of the present invention provide a system and method for monitoring an electric motor.
In one aspect, an embodiment of the present invention provides a system for monitoring an electric motor, characterized in that the system for monitoring an electric motor includes: the distributed control system analog input clamping piece, the current value adjusting unit and the monitoring unit;
The current value adjusting unit is connected between the analog quantity input clamping piece of the decentralized control system and the external transmitter, so that response current generated by the external transmitter based on working current of the motor is received, and when the current value of the response current is larger than an alarm current value for triggering alarm of the analog quantity input clamping piece of the decentralized control system, the current value of the response current is adjusted, so that the adjusted current value of the response current is smaller than the alarm current value, and the response current with the adjusted current value is provided for the analog quantity input clamping piece of the decentralized control system; the distributed control system analog input card is connected with the monitoring unit so as to supply the response current with the adjusted current value received from the current value adjusting unit to the monitoring unit, so that the monitoring unit monitors the operating state of the motor based on the response current with the adjusted current value.
In some embodiments, the current value adjustment unit includes a control unit and a current limiting unit;
The control unit is connected to the external transmitter and is configured to: receiving the response current from the external transmitter; measuring a current value of the response current; determining whether a current value of the response current is less than the alarm current value based on the measured current value; when the control unit determines that the current value of the response current is greater than or equal to the alarm current value, sending a first control signal to the current limiting unit, wherein the first control signal is used for instructing the current limiting unit to adjust the current value of the response current so that the adjusted current value of the response current is smaller than the alarm current value;
the current limiting unit is connected to the control unit, and the current limiting unit is configured to: receiving the first control signal from the control unit; and adjusting the current value of the response current based on the first control signal so that the adjusted current value of the response current is smaller than the alarm current value.
In some embodiments, when the control unit determines that the current value of the response current is less than the alarm current value, the control unit sends a second control signal to the current limiting unit, the second control signal being used to instruct the current limiting unit to directly provide the response current received from the external transmitter to the decentralized control system analog input card;
the current limiting unit receives the second control signal from the control unit, and the current limiting unit directly provides the response current received from the external transmitter to the decentralized control system analog input card based on the second control signal.
In some embodiments, the current limiting unit is a resistor having a predetermined resistance value selected between a maximum resistance value and a minimum resistance value; the maximum resistance value is determined based on the load capacity of the external transmitter and an inherent resistance value, wherein the inherent resistance value is the sum of a cable resistance value and an internal resistance value of the distributed control system analog input clamping piece, and the cable resistance value is the resistance value of a cable connected between the distributed control system analog input clamping piece and the external transmitter; the minimum resistance value is determined based on the maximum output power of the external transmitter, an alarm current value that triggers an alarm of the distributed control system analog input card, and the intrinsic resistance value.
In some embodiments, the current limiting unit is an adjustable resistor having an adjustable resistance value ranging from 0 to a maximum resistance value;
when the adjustable resistor is used to adjust the current value of the response current received from the external transmitter, the resistance value of the adjustable resistor is selected between a minimum resistance value and a maximum resistance value;
When the adjustable resistor is used to provide the response current received from the external transmitter directly to the decentralized control system analog input clamp, the resistance value of the adjustable resistor is selected between 0 and the minimum resistance value and is less than the minimum resistance value;
The maximum resistance value is determined based on the load capacity of the external transmitter and an inherent resistance value, wherein the inherent resistance value is the sum of a cable resistance value and an internal resistance value of the distributed control system analog input clamping piece, and the cable resistance value is the resistance value of a cable connected between the distributed control system analog input clamping piece and the external transmitter; the minimum resistance value is determined based on the maximum output power of the external transmitter, an alarm current value that triggers an alarm of the distributed control system analog input card, and the intrinsic resistance value.
In some embodiments, the current value adjusting unit is a resistor having a predetermined resistance value, the predetermined resistor being selected between a maximum resistance value and a minimum resistance value;
The maximum resistance value is determined based on the load capacity of the external transmitter and an inherent resistance value, wherein the inherent resistance value is the sum of a cable resistance value and an internal resistance value of the distributed control system analog input clamping piece, and the cable resistance value is the resistance value of a cable connected between the distributed control system analog input clamping piece and the external transmitter; the minimum resistance value is determined based on the maximum output power of the external transmitter, an alarm current value that triggers an alarm of the distributed control system analog input card, and the intrinsic resistance value.
In some embodiments, the maximum resistance value = the load capacity of the external transmitter-the intrinsic resistance value;
The minimum resistance value= (maximum output power of the external transmitter/(the alarm current value x the alarm current value)) -the intrinsic resistance value.
Drawings
The above and other objects, features and advantages of embodiments of the present specification will become more apparent from the more detailed description of embodiments thereof, taken in conjunction with the accompanying drawings in which like reference characters generally represent like elements throughout the embodiments of the present specification.
Fig. 1 is a schematic view of a DCS monitoring motor.
Fig. 2 is a schematic view of a scenario in which a motor is monitored by a system for monitoring the motor according to some embodiments.
Fig. 3A is a schematic diagram of an implementation example of the current value adjustment unit.
Fig. 3B is a schematic diagram of an example implementation of a current limiting unit.
FIG. 4A is a schematic diagram of one way of connecting the current value adjustment unit to the DCS analog input card and the transmitter.
FIG. 4B is a schematic diagram of another connection of the current value adjustment unit to the DCS analog input clamp and the transmitter.
List of reference numerals:
102: DCS analog input card 104: transmitter
106: Motor 108: monitoring unit
200: System for monitoring motors 202: DCS analog input clamping piece
208: The monitoring unit 210: current value adjusting unit
212: Control unit 214: current limiting unit
222: Switching element 224: resistor
2121: Positive input terminal 2122: negative input terminal
Detailed Description
The subject matter described herein will now be discussed with reference to various embodiments. It should be appreciated that these embodiments are discussed only to enable those skilled in the art to better understand and practice the subject matter described herein and are not limiting on the scope, applicability, or examples set forth in the claims. Changes may be made in the function and arrangement of elements discussed without departing from the scope of the claims. Various embodiments may omit, replace, or add various procedures or components as desired.
As used herein, the term "comprising" and variations thereof mean open-ended terms, meaning "including, but not limited to. The term "based on" means "based at least in part on". The terms "one embodiment" and "an embodiment" mean "at least one embodiment. The term "another embodiment" means "at least one other embodiment". The terms "first," "second," and the like, may refer to different or the same object. Other definitions may be included, whether explicit or implicit, and the definition of a term is consistent throughout this specification unless the context clearly indicates otherwise.
DCS has been widely used in power plant production environments to monitor and manage various production facilities. For example, the DCS may monitor the operating current of the motor through an external transmitter. For example, the transmitter may sense an operating current of the motor and generate a response current based on the sensed operating current. The DCS may include a DCS analog input card. DCS analog input cards are typically used to receive analog quantities (e.g., voltages, currents, etc.) associated with a monitored device that may reflect the operating state of the monitored device, such as operating current, voltage, temperature, pressure, etc. For example, one example of a DCS analog input card may be analog input card FUM230 in the siemens T2000 system. It should be noted, however, that the DCS analog input card referred to in the embodiments herein is not limited to this particular example, and may be any analog input card capable of receiving an analog quantity associated with a device being tested.
Typically, the DCS analog input card can be connected to the transmitter (e.g., via a cable). The transducer can provide the response current generated by the transducer to the DCS analog input clamping piece. In addition, in the DCS, the DCS analog input card may be connected to the monitoring unit so that the DCS analog input card may supply the response current received by the DCS analog input card to the monitoring unit. The monitoring unit may monitor an operating state of the motor based on the response current.
Fig. 1 is a schematic view of a DCS monitoring motor. As shown in fig. 1, the DCS may include a DCS analog input card 102 and a monitoring unit 108. Transmitter 104 may be external to the DCS. Further, the transmitter 104 can be coupled to the motor 106 and can sense an operating current of the motor 106. It should be appreciated that depending on the particular implementation of the transmitter 104, the transmitter 104 may be coupled to the motor 106 in a variety of ways, such as a direct physical connection, inductive coupling, and so forth.
The transmitter 104 can generate a corresponding response current based on the sensed operating current of the motor. For example, the transmitter 104 can generally convert the operating current of the motor to a response current in a certain proportion. Currently, commonly used transmitters can output a response current in the range of 4-20mA under rated conditions.
Transmitter 104 may provide a response current to DCS analog input clamp 102. The DCS analog input card 102 may provide the received response current to the monitoring unit 108. The monitoring unit 108 may monitor the operating state of the motor based on the response current. It should be understood that in particular practice, the DCS may also include other various components. Other components of the DCS are not shown in fig. 1 for simplicity of illustration herein.
Typically, the response current produced by the transducer is proportional to the operating current of the motor. Thus, the greater the operating current of the motor, the greater the response current generated by the transducer. In some cases, the working current of the motor may be so large that the current value of the response current generated by the transmitter is greater than or equal to the alarm current value for triggering the DCS analog input clamping member to alarm, thereby triggering the DCS analog input clamping member to alarm and further triggering the fault protection thereof, thereby affecting the efficient monitoring of the motor and affecting the normal production process.
For example, depending on the characteristics of the motor, the current of the motor may be several times the rated operating current during the start-up phase of the motor, and the current value of the response current generated by the transducer will be several times the normal value. For example, in the case of conventional current transformers, the current involved is measured in situ. Table 1 below shows an example of the relationship between the response current produced by the transducer and the current of the motor.
Table 1 relationship between the response current produced by the transducer and the current of the motor (field measurement result)
It can be seen that, based on the field measurements, the current value of the response current generated by the transducer exceeds 60mA during start-up of the motor. For the Siemens T2000 system, the alarm current value of the analog input clamp FUM230 is 40mA. Thus, when the current value of the response current generated by the transmitter is greater than or equal to 40mA, the analog input clamping piece is triggered to alarm, and the fault protection is caused, so that the efficient monitoring of the motor is affected. In some implementations, the operator may ignore such alarms first, and manually reset the previous alarms after motor start-up is complete. This approach may increase labor costs. In some implementations, however, to avoid such alarms, it is possible to replace a larger range transmitter. This approach may increase equipment costs and also present a problem of construction time.
In view of this, embodiments of the present invention provide a solution for monitoring an electric motor. This technical scheme will be described below in connection with various embodiments.
Fig. 2 is a schematic diagram of a system for monitoring an electric motor according to some embodiments.
As shown in fig. 2, a system 200 for monitoring a motor 106 may include a DCS analog input card 202, a current value adjusting unit 210, and a monitoring unit 208. The current value adjustment unit 210 may be connected between the DCS analog input card 202 and the external transmitter 104. It should be understood that "external" is used herein to indicate that transmitter 104 is external to system 200. Hereinafter, for the sake of brevity, description will be made using the "transmitter" without specific emphasis of "outside".
The current value adjustment unit 210 can receive a response current generated by the transmitter 104 based on an operating current of the motor. In addition, the current value adjustment unit 210 may limit the current value of the response current to be smaller than an alarm current value that triggers an alarm of the DCS analog input card 202. For example, the current value adjustment unit 210 may limit the maximum current value of the response current to be less than the alarm current value of the DCS analog input card 202. The current value adjustment unit 210 may provide the response current to the DCS analog input card 202.
For example, the current value adjusting unit 210 may adjust the current value of the response current such that the adjusted current value of the response current is smaller than the alarm current value when the current value of the response current is greater than the alarm current value, and provide the response current having the adjusted current value to the DCS distributed control system analog input card 202.
The DCS analog input card 202 may be connected to a monitoring unit 208. The DCS analog input card 202 may provide the response current received from the current value adjusting unit 210 to the monitoring unit 208. The monitoring unit 208 may monitor the operating state of the motor according to the response current.
It can be seen that, in the embodiment herein, since the current value adjusting unit is added between the DCS analog input card and the transmitter, the current value adjusting unit can limit the current value of the response current to be smaller than the alarm current value for triggering the DCS analog input card to alarm, so that the fault protection of the DCS analog input card caused by that the current value of the response current is greater than or equal to the alarm current value can be avoided.
Therefore, the influence of DCS analog input clamping piece fault protection on a normal monitoring motor can be reduced, and the production efficiency is improved. In addition, the mode can avoid unnecessary manual operation, and the large-range transmitter does not need to be replaced, so that the equipment cost is saved. In addition, the mode also does not need to lay cables again, so that the production cost can be reduced.
In an embodiment of the invention, the transmitter may be a current mode transmitter.
In an embodiment of the present invention, the current value adjusting unit 210 may be implemented in various different manners.
Fig. 3A shows a block diagram of an example of implementation of the current value adjustment unit. In order to more clearly show the current value adjustment unit, the motor 106 and the monitoring unit 208 are not shown in fig. 3A.
As shown in fig. 3A, the current value adjusting unit 210 may include a control unit 212 and a current limiting unit 214. Control unit 212 can be coupled to transmitter 104 and current limiting unit 214. The control unit 212 can detect the magnitude of the current value of the response current of the transmitter 104 and control the current limiting unit 220 to limit the response current or not based on the detection result.
For example, the control unit 212 may control the current limiting unit 210 to limit the response current when detecting that the current value of the response current is greater than or equal to the alarm current value. The control unit 212 may control the current limiting unit 210 to directly supply the response current to the DCS analog input card without limiting the current when it is detected that the current value of the response current is smaller than the alarm current value.
Specifically, control unit 212 can receive a response current from transmitter 104, measure a current value of the response current, and determine whether the current value of the response current is less than an alarm current value based on the measured current value of the response current.
When the control unit 212 determines that the current value of the response current is greater than or equal to the alarm current value, the control unit 212 transmits a first control signal to the current limiting unit 214. The first control signal may be used to instruct the current limiting unit 214 to adjust the current value of the response current to be less than the alarm current value.
In this way, the current limiting unit 214 may adjust the current value of the response current to be smaller than the alarm current value after receiving the first control signal.
When the control unit 212 determines that the current value of the response current is smaller than the alarm current value, a second control signal is transmitted to the current limiting unit 214. The second control signal may be used to instruct the current limiting unit 214 to provide the response current received from the transmitter 104 directly to the DCS analog input card 202 without adjustment.
The current limiting unit 214 can provide the response current received from the transducer 104 directly to the DCS analog input card 202 after receiving the second control signal.
The current limiting unit 214 may be implemented in a variety of suitable ways. Fig. 3B shows a block diagram of an example implementation of the current limiting unit 214. As shown in fig. 3B, the current limiting unit 214 may include a switching element 222 and a resistor 224. Switching element 222 can be connected between DCS analog input clamp 202 and transmitter 104 and in parallel with resistor 224.
When the control unit 212 determines that the current value of the response current is greater than or equal to the alarm current value, the control unit 212 may generate a first control signal for turning off the switching element 222. When switching element 222 is open, transmitter 104 provides a response current to resistor 224, and resistor 224 can limit the response current, i.e., adjust its current value, to be less than the alarm current value. Resistor 224 then provides the adjusted response current to DCS analog input clamp 202.
When the control unit 212 determines that the current value of the response current is smaller than the alarm current value, the control unit 212 may be used for a second control signal to close the switching element 222. When the switching element 222 is closed, the resistor 224 is shorted and a response current may enter the DCS analog input clamp 202 via the switching element 222 without the resistor 224 limiting current.
Here, the resistance value of the resistor 224 may be selected between a maximum resistance value and a minimum resistance value described below.
In other embodiments, the current limiting unit 214 may be a resistor having a predetermined resistance value. The predetermined resistance value may be selected between a maximum resistance value and a minimum resistance value described below.
In other embodiments, the current limiting unit 214 may be an adjustable resistor. The adjustable resistor has an adjustable resistance value ranging from 0 to the maximum resistance value described below,
When the adjustable resistor is used to adjust the current value of the response current received from the external transmitter, the resistance value of the adjustable resistor is selected between a minimum resistance value and a maximum resistance value described below,
When the adjustable resistor is used to provide the response current received from the external transmitter directly to the DCS analog input clamp, the resistance value of the adjustable resistor is selected between 0 and a minimum resistance value described below and is less than the minimum resistance value.
In other embodiments, the current value adjusting unit 210 may itself be a resistor, which may have a resistance value selected between a maximum resistance value and a minimum resistance value described below.
In the embodiments herein, when the operating current of the motor is large (e.g., during start-up of the motor), the response current generated by the transducer will also be limited because the output power of the transducer is limited and the resistor cannot be burdened with the consumption of high current. Therefore, by properly setting the resistance value of the resistor connected between the DCS analog input card and the transmitter, after the output power of the transmitter reaches the maximum output power, the maximum value of the response current will remain unchanged and smaller than the alarm current value of the DCS analog input card due to the limiting effect of the resistor, thereby effectively avoiding the initiation of the DCS analog input card fault protection. It can be seen that this way an efficient monitoring of the motor can be achieved.
In some embodiments, current value adjustment unit 210 can be connected between transmitter 104 and DCS analog input card 202 in various ways. Specifically, DCS analog input card 202 may include a positive input terminal and a negative input terminal. The output of transmitter 104 can include a positive output terminal and a negative output terminal. It will be appreciated herein that "positive" and "negative" may refer to the direction of flow of current.
FIG. 4A shows one way of connecting the current value adjustment unit 210 to the DCS analog input card and the transmitter. As shown in fig. 4A, current value adjustment unit 210 can be connected between a positive input terminal 2121 of DCS analog input card 202 and a positive output terminal of transmitter 104. While the negative input terminal 2122 of the DCS analog input card 202 can be directly connected to the negative output terminal of the transmitter 104.
FIG. 4B shows another way of connecting the current value adjustment unit 210 to the DCS analog input card and the transmitter. As shown in fig. 4B, current value adjustment unit 210 can be connected between negative input terminal 2122 of DCS analog input card 202 and the negative output terminal of transmitter 104. While the positive input terminal 2121 of DCS analog input clip 202 can be directly connected to the positive output terminal of transmitter 104.
It should be appreciated that the monitoring unit 208 is not shown in fig. 4A and 4B for simplicity of illustration.
In some cases, these connections may be made through cables.
How the above-described maximum resistance value and minimum resistance value are determined will now be described in detail. The maximum and minimum resistance values can be determined based on the load capacity of the transmitter 104, the maximum output power of the transmitter 104, the intrinsic resistance value, and the alarm current value of the DCS analog input card 202.
Here, the intrinsic resistance value may be a sum of a cable resistance value and an internal resistance value of the DCS analog input card 202 itself. Here, the internal resistance value of the DCS analog input card 202 itself may refer to an equivalent resistance value between the input and output ends of the DCS analog input card 202, that is, an equivalent resistance value inside the card 202. The cable resistance value may be the resistance value of the cable itself, i.e., the equivalent resistance value of the cable itself, between the input channel 212 of the DCS analog input clamp 202 and the output of the transmitter 104.
In general, the load capacity of the transmitter 104 can define a maximum resistance value that allows access to the transmitter's output loop under nominal operating conditions (e.g., 4-20 mA). Within this range of maximum resistance values, the transmitter can operate normally (e.g., the operating current of the motor can be converted to 4-20mA in a set ratio). Thus, after adding the resistor, the total loop resistance value of the output connection of the transmitter should not be greater than the load carrying capability of the transmitter.
It can be seen that the maximum resistance value described above can be determined based on the load carrying capacity and the inherent resistance value of the transmitter 104. For example, the above maximum resistance value may be calculated as follows: maximum resistance = load capacity of the transmitter-intrinsic resistance.
Further, the maximum output power of the transmitter may define the maximum power that the transmitter can output. And as previously described, when the output power of the transmitter reaches the maximum output power, the resistance value of the resistor as the current limiting unit 210 may be such that the maximum value of the response current does not exceed the alarm current value of the DCS analog input card.
Accordingly, the minimum resistance value can be determined based on the maximum output power of the transmitter 104, the alarm current value of the DCS analog input clamp 202, and the intrinsic resistance value.
As is known, the power calculation formula may be: power = current x voltage. Further, the formula may be modified as: power = current x resistance
Then, in embodiments herein, the minimum resistance value may be calculated according to the following equation: maximum output power of transmitter = alarm current value x (minimum resistance value + intrinsic resistance value).
Deriving based on the equation may yield:
Minimum resistance value= (maximum output power of transmitter/(alarm current value×alarm current value)) -intrinsic resistance value
After the maximum resistance value and the minimum resistance value are determined, a specific resistance value as the above-described resistor or the tunable resistor may be selected within this range according to the actual situation. Therefore, the mode is simple in implementation, and can flexibly meet various field requirements.
For ease of understanding, the following description is provided in connection with specific examples. It should be understood that the following examples do not limit the scope of the technical solutions herein.
Assuming that the normal range of response current for the transmitter 104 is 4-20mA, that is, at nominal operating conditions (4-20 mA), the transmitter 104 can operate normally. In addition, assume that the maximum load capacity of transmitter 104 is 800 ohms.
In the case of using the DCS analog of siemens T2000 to input the card FUM230, the sum of the internal resistance value of the card and the resistance value of the cable was 80 ohms through actual measurement. That is, the intrinsic resistance value is 80 ohms.
Therefore, in the case where the current value adjusting unit 210 is a resistor, the maximum resistance value with respect to the resistor should be 800-80=720 ohms.
Further, assume that the maximum output power of transmitter 104 is 0.32 watts. Since the alarm current value of clamp FUM230 is 40mA, the minimum resistance value allowed to access the output loop of transmitter 104 is 0.32 watts/(0.04 a x 0.04 a) =200 ohms.
And the intrinsic resistance value is 80 ohms, the minimum resistance value for this resistor should be 200-80 = 120 ohms.
Accordingly, the resistance value of the resistor may be selected in the range of 120 ohms to 720 ohms.
In a practical test, a resistor with 250 ohms was selected.
By theoretical calculation, in the case of a 250 ohm resistor, the response current can be determined to be 31.14mA at maximum according to the equation 0.32=i 2 x (250+80) (where I can represent the maximum value of the response current). This is 40mA below the alarm current value of clip FUM230 and therefore does not trigger a clip alarm.
Table 2 gives the field measurements for the example above with a 250 ohm resistor connected between clamp FUM230 and the transmitter. As shown in Table 2, the response current was 30.98mA at maximum, which basically corresponds to the theoretical calculation described above. It can also be seen that under nominal operating conditions, the resistor acting as current limiting unit 210 does not affect the proper operation of transmitter 104.
Table 2 relationship between the response current produced by the transducer and the current of the motor (field measurement result)
Therefore, the resistor is added between the DCS analog input clamping piece and the transmitter, so that the maximum value of the response current output by the transmitter is smaller than the alarm current value of the DCS analog input clamping piece, and clamping piece fault protection caused by that the response current is larger than or equal to the alarm current value of the DCS analog input clamping piece can be avoided, and the motor can be monitored efficiently.
Not all illustrated blocks or steps may be required in the above described structures or flow diagrams, and some of the blocks or steps may be omitted as may be practical. The apparatus structures described in the above embodiments may be physical structures or logical structures, that is, some units may be implemented by the same physical entity, or some units may be implemented by a plurality of physical entities respectively, or may be implemented jointly by some components in a plurality of independent devices.
The term "exemplary" used throughout this specification means "serving as an example, instance, or illustration," and does not mean "preferred" or "advantageous over other embodiments. The detailed description includes specific details for the purpose of providing an understanding of the described technology. However, the techniques may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the described embodiments.
The alternative implementation of the embodiment of the present disclosure has been described in detail above with reference to the accompanying drawings, but the embodiment of the present disclosure is not limited to the specific details of the foregoing implementation, and various modifications may be made to the technical solutions of the embodiment of the present disclosure within the scope of the technical concept of the embodiment of the present disclosure, which all fall within the protection scope of the embodiment of the present disclosure.
The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (5)
1. A system (200) for monitoring an electric motor (106), the system (200) for monitoring an electric motor (106) comprising:
a distributed control system analog input card (202), a current value adjusting unit (210) and a monitoring unit (208);
The current value adjusting unit (210) is connected between the distributed control system analog input clamping piece (202) and the external transmitter (104), so as to receive response current generated by the external transmitter (104) based on working current of the motor (106), and adjust the current value of the response current when the current value of the response current is larger than an alarm current value for triggering alarm of the distributed control system analog input clamping piece (202), so that the adjusted current value of the response current is smaller than the alarm current value, and provide the response current with the adjusted current value to the distributed control system analog input clamping piece (202);
The distributed control system analog input card (202) is connected with the monitoring unit (208) so as to supply the response current received from the current value adjusting unit (210) to the monitoring unit (208) so that the monitoring unit (208) monitors the operating state of the motor (106) based on the response current,
Wherein the current value adjusting unit (210) comprises a control unit (212) and a current limiting unit (214),
Wherein the current limiting unit (214) is a resistor having a predetermined resistance value, the predetermined resistance value being selected between a maximum resistance value and a minimum resistance value,
The maximum resistance value is determined based on the load carrying capacity of the external transmitter (104) and an intrinsic resistance value that is a sum of a cable resistance value and an internal resistance value of the decentralized control system analog input card (202) itself, the cable resistance value being a resistance value of the cable itself connected between the decentralized control system analog input card (202) and the external transmitter (104),
The minimum resistance value is determined based on a maximum output power of the external transmitter (104), an alarm current value that triggers an alarm of the decentralized control system analog input card (202), and the intrinsic resistance value.
2. The system (200) for monitoring a motor (106) of claim 1, wherein,
The control unit (212) is connected to the external transmitter (104), and the control unit (212) is configured to:
Receiving the response current from the external transmitter (104);
measuring a current value of the response current;
Determining whether a current value of the response current is less than the alarm current value based on the measured current value;
when the control unit (212) determines that the current value of the response current is greater than or equal to the alarm current value, sending a first control signal to the current limiting unit (214), wherein the first control signal is used for instructing the current limiting unit (214) to adjust the current value of the response current so that the adjusted current value of the response current is smaller than the alarm current value;
The current limiting unit (214) is connected to the control unit (212), and the current limiting unit (214) is configured to:
-receiving the first control signal from the control unit (212);
And adjusting the current value of the response current based on the first control signal so that the adjusted current value of the response current is smaller than the alarm current value.
3. The system (200) for monitoring a motor (106) of claim 2, wherein,
When the control unit (212) determines that the current value of the response current is smaller than the alarm current value, the control unit (212) sends a second control signal to the current limiting unit (214), wherein the second control signal is used for instructing the current limiting unit (214) to directly provide the response current received from the external transmitter to the distributed control system analog input clamping piece;
The current limiting unit (214) receives the second control signal from the control unit (212), and the current limiting unit (214) provides the response current received from the external transmitter (104) directly to the decentralized control system analog input card (202) based on the second control signal.
4. A system (200) for monitoring an electric motor (106), the system (200) for monitoring an electric motor (106) comprising:
a distributed control system analog input card (202), a current value adjusting unit (210) and a monitoring unit (208);
The current value adjusting unit (210) is connected between the distributed control system analog input clamping piece (202) and the external transmitter (104), so as to receive response current generated by the external transmitter (104) based on working current of the motor (106), and adjust the current value of the response current when the current value of the response current is larger than an alarm current value for triggering alarm of the distributed control system analog input clamping piece (202), so that the adjusted current value of the response current is smaller than the alarm current value, and provide the response current with the adjusted current value to the distributed control system analog input clamping piece (202);
The distributed control system analog input card (202) is connected with the monitoring unit (208) so as to supply the response current received from the current value adjusting unit (210) to the monitoring unit (208) so that the monitoring unit (208) monitors the operating state of the motor (106) based on the response current,
Wherein the current value adjusting unit (210) comprises a control unit (212) and a current limiting unit (214),
Wherein the current limiting unit (214) is an adjustable resistor, and the adjustable resistance value of the adjustable resistor ranges from 0 to a maximum resistance value;
when the adjustable resistor is used to adjust the current value of the response current received from the external transmitter (104), the resistance value of the adjustable resistor is selected between a minimum resistance value and a maximum resistance value;
When the adjustable resistor is used to provide the response current received from the external transmitter (104) directly to the distributed control system analog input card (202), the resistance value of the adjustable resistor is selected between 0 and the minimum resistance value and is less than the minimum resistance value;
The maximum resistance value is determined based on the load carrying capacity of the external transmitter (104) and an intrinsic resistance value that is a sum of a cable resistance value and an internal resistance value of the decentralized control system analog input card (202) itself, the cable resistance value being a resistance value of the cable itself connected between the decentralized control system analog input card (202) and the external transmitter (104),
The minimum resistance value is determined based on a maximum output power of the external transmitter (104), an alarm current value that triggers an alarm of the decentralized control system analog input card (202), and the intrinsic resistance value.
5. The system (200) for monitoring the motor (106) of claim 4, wherein,
The maximum resistance value = the load capacity of the external transmitter-the intrinsic resistance value;
The minimum resistance value= (maximum output power of the external transmitter/(the alarm current value x the alarm current value)) -the intrinsic resistance value.
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| CN202661855U (en) * | 2012-06-08 | 2013-01-09 | 瓮福（集团）有限责任公司 | Monitoring system of running state of control system |
| CN104779597A (en) * | 2015-04-29 | 2015-07-15 | 广东电网有限责任公司中山供电局 | Electric system current limiting protecting equipment and protecting method thereof |
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| JP2001125651A (en) * | 1999-10-25 | 2001-05-11 | Ando Electric Co Ltd | Current limiting circuit |
| CN201583623U (en) * | 2010-01-05 | 2010-09-15 | 沈阳计量测试院 | Calibrating device of leakage current tester |
| KR101874584B1 (en) * | 2012-04-03 | 2018-07-04 | 삼성전자주식회사 | Voltage Mode Driver |
| CN203217349U (en) * | 2013-04-19 | 2013-09-25 | 新疆新路标光伏材料有限公司 | Raymond mill distributed control system |
| US10163324B2 (en) * | 2016-09-26 | 2018-12-25 | Siemens Industry, Inc. | Remote battery monitor |
| CN107170188B (en) * | 2017-07-07 | 2023-05-05 | 金川集团股份有限公司 | Adjustable audible and visual alarm device for DCS system and use method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN202661855U (en) * | 2012-06-08 | 2013-01-09 | 瓮福（集团）有限责任公司 | Monitoring system of running state of control system |
| CN104779597A (en) * | 2015-04-29 | 2015-07-15 | 广东电网有限责任公司中山供电局 | Electric system current limiting protecting equipment and protecting method thereof |
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