1 The design of the ACM monitoring device is based on Section 4.3.5 of the "Low Voltage Distribution Design Code" (GB 50054-95): "Sudden power-off is more severe than loss caused by overload, and the overload protection should act on the signal. Should not act on the cut-off circuit." This article states: "The overload of the line has not yet become a short circuit. Short-term overloading does not immediately cause disaster. In some cases, the conductor can exceed the allowable temperature to run, that is, sacrifice. Some service life to ensure that the power supply to certain loads is not interrupted, such as the load of a fire pump, the protection can act on the signal.â€
“Civil Building Electrical Design Specification†JGJ 16-2008, Clause 7.6.5, stipulates, “Sudden power outage is greater than the line loss caused by overload, and its overload protection should act on the signal and should not cut off the circuit†This is a mandatory clause and must be observed. There are two objects for overload protection: one is the fire fighting equipment, that is, the electric motor; the other is the wiring for the distribution of these fire fighting equipment. This article is an important introduction to the latter, that is, how to use ACM to implement the overload alarm function of distribution lines to meet the requirements of the mandatory provisions of the specification.
Miniature circuit breakers and molded case circuit breakers are commonly used in power distribution design. Among them, miniature circuit breakers are mainly used in overcurrent protection in homes and similar places. The rated current is not more than 125A. Most of the applications in industrial applications are molded case circuit breakers.
2 Basic principle of ACM monitoring device 2.1 Principle of monitoring device The ACM power distribution line overload monitoring device adopts the latest 32-bit microcontroller technology and has the characteristics of strong anti-interference ability, stable and reliable operation, digitization, and network. By detecting the current of the line, a two-stage alarm of the distribution circuit is realized. The monitoring device can have current, voltage, active power, reactive power, apparent power, power factor, leakage current measurement function, current 2-15th harmonic analysis function, built-in buzzer, indicator alarm function, alarm event Record, RS485 Modbus-RTU, Profibus-DP protocol communication interface, switch input, programmable relay output, DC 4~20mA analog output and other functions, it is convenient to form a network with PLC, IPC and other industrial control equipments to achieve remote monitoring of line operation. .
2.2 Main functions 1) Load current monitoring In the distribution circuit, the monitoring device can be used in conjunction with miniature circuit breakers and molded case circuit breakers respectively (the circuit breakers at this time should be single magnetic trip circuit breakers). See Table 2 for alarm sections. Taking a molded case circuit breaker as an example, when the load current exceeds the alarm value of segment 1 overload 1.05In, the alarm 1 instantaneously alarms; when the load current exceeds the overload value of alarm 2 segment 1.3 In, when the range of (1.3 ~ 4) In, the alarm delay When the alarm, follow the anti-time limit principle, the greater the load current, the shorter the alarm delay time.
2) Leakage current monitoring By measuring the leakage current in the main circuit, the leakage current is monitored and alarmed via the D01 (95, 96) relay or internal buzzer.
3) The measurement function has the functions of measuring phase voltage, line voltage, phase current, current and rated current overload percentage, active power, reactive power, power factor, frequency, leakage current and harmonics.
3 Fire Fighting Applications There are many fire fighting equipments. In addition to fire fighting pumps, there are fire extinguishers, anti-exhaust fans, and fire shutter doors. Some of them are electricity and some are lighting; some have backup units. Some are not used; others are only used during firefighting, and some are usually used for long-term use only as fire-fighting equipment, such as exhaust fans and exhaust fans, fire elevators and passenger elevators, normal lighting and emergency lighting. The nature of the load and use are not the same. For those equipment that is normally used for firefighting and its distribution lines, the most appropriate method is to adopt certain technical measures to achieve overload shut-off of the power supply during normal use and an overload alarm in case of fire conditions. You can use ACM series monitoring devices:
1) When the load current exceeds a certain alarm threshold, the monitoring device can send an alarm indication through the indicator light, the load current continues to increase. When the alarm threshold exceeds the second stage, the monitoring device alarms through the indicator light and the buzzer;
2) Leakage current alarm function can be used to measure the leakage current through the leakage current in the circuit, which is also an effective method of fire monitoring;
3) The monitoring device can monitor the opening and closing state of the circuit breaker in the circuit through two switching inputs. Besides the ACM monitoring device itself can alarm, it also has a programmable relay output, which can be one alarm, two alarms, and leakage current. Or the state of the circuit breaker is output to facilitate linkage control.
4) ACM monitoring device can have 4 ~ 20mA analog output and RS485 Modbus-RTU communication, Profibus-DP communication, easy to monitor the host computer.
4 The application of ACM in practice The ACM monitoring device is used in combination with a molded case circuit breaker. The molded case circuit breaker has two kinds of single magnetic and thermal magnetic. The single magnetic circuit breaker has only short circuit protection function and no thermal overload protection. Under the circumstances, if there is overload in the circuit, the circuit breaker will not act, and the ACM monitoring device will issue an alarm signal according to different overload levels to remind the on-site maintenance personnel to also remotely transmit to the control center. The thermal magnetic molded case circuit breaker has both short-circuit protection and thermal overload protection. At this time, the ACM monitoring device can only function as an alarm function. When the detected current reaches the set threshold, the internal relay operates.
The current transformer used by the monitoring device uses the AKH-0.66 series current transformer. If the rated current of the distribution line is 32A, and the transformer is AKH-0.66-60/5, this type of transformer has 2In range measurement and monitoring device. The maximum sustainable measurement current reaches 10A, so the device can monitor up to 4 times the overload current. The AKH-0.66L series residual current transformers are also required for applications requiring monitoring of residual current loops. In the figure above, when the current of the distribution line exceeds the alarm threshold of one stage, the relay (7, 8) is closed, the first stage of alarm output, the KA1 coil is energized, and the PGR light alarms; when the load level increases, the alarm threshold of two stages is reached. The relays (9, 10) are closed, 2 sections of alarm output, KA2 coils are powered, PG sounds alarm. When the audible and visual alarm release button is pressed or the load current decreases, the alarm state is released. The digital input can upload the circuit breaker's closing and tripping status to the background control center, and another programmable relay can be used as remote control or leakage current alarm output. Refer to the ACM overload monitoring device for details. .
5 Conclusion ACM series distribution line overload monitoring device two-stage alarm, the alarm follows the anti-time limit principle, the greater the degree of overload, the faster the alarm speed, in line with the site conditions. At the same time, the design method of the device meets the requirements of the standard well and is worthy of being used by the majority of electrical designers.
“Civil Building Electrical Design Specification†JGJ 16-2008, Clause 7.6.5, stipulates, “Sudden power outage is greater than the line loss caused by overload, and its overload protection should act on the signal and should not cut off the circuit†This is a mandatory clause and must be observed. There are two objects for overload protection: one is the fire fighting equipment, that is, the electric motor; the other is the wiring for the distribution of these fire fighting equipment. This article is an important introduction to the latter, that is, how to use ACM to implement the overload alarm function of distribution lines to meet the requirements of the mandatory provisions of the specification.
Miniature circuit breakers and molded case circuit breakers are commonly used in power distribution design. Among them, miniature circuit breakers are mainly used in overcurrent protection in homes and similar places. The rated current is not more than 125A. Most of the applications in industrial applications are molded case circuit breakers.
2 Basic principle of ACM monitoring device 2.1 Principle of monitoring device The ACM power distribution line overload monitoring device adopts the latest 32-bit microcontroller technology and has the characteristics of strong anti-interference ability, stable and reliable operation, digitization, and network. By detecting the current of the line, a two-stage alarm of the distribution circuit is realized. The monitoring device can have current, voltage, active power, reactive power, apparent power, power factor, leakage current measurement function, current 2-15th harmonic analysis function, built-in buzzer, indicator alarm function, alarm event Record, RS485 Modbus-RTU, Profibus-DP protocol communication interface, switch input, programmable relay output, DC 4~20mA analog output and other functions, it is convenient to form a network with PLC, IPC and other industrial control equipments to achieve remote monitoring of line operation. .
2.2 Main functions 1) Load current monitoring In the distribution circuit, the monitoring device can be used in conjunction with miniature circuit breakers and molded case circuit breakers respectively (the circuit breakers at this time should be single magnetic trip circuit breakers). See Table 2 for alarm sections. Taking a molded case circuit breaker as an example, when the load current exceeds the alarm value of segment 1 overload 1.05In, the alarm 1 instantaneously alarms; when the load current exceeds the overload value of alarm 2 segment 1.3 In, when the range of (1.3 ~ 4) In, the alarm delay When the alarm, follow the anti-time limit principle, the greater the load current, the shorter the alarm delay time.
2) Leakage current monitoring By measuring the leakage current in the main circuit, the leakage current is monitored and alarmed via the D01 (95, 96) relay or internal buzzer.
3) The measurement function has the functions of measuring phase voltage, line voltage, phase current, current and rated current overload percentage, active power, reactive power, power factor, frequency, leakage current and harmonics.
3 Fire Fighting Applications There are many fire fighting equipments. In addition to fire fighting pumps, there are fire extinguishers, anti-exhaust fans, and fire shutter doors. Some of them are electricity and some are lighting; some have backup units. Some are not used; others are only used during firefighting, and some are usually used for long-term use only as fire-fighting equipment, such as exhaust fans and exhaust fans, fire elevators and passenger elevators, normal lighting and emergency lighting. The nature of the load and use are not the same. For those equipment that is normally used for firefighting and its distribution lines, the most appropriate method is to adopt certain technical measures to achieve overload shut-off of the power supply during normal use and an overload alarm in case of fire conditions. You can use ACM series monitoring devices:
1) When the load current exceeds a certain alarm threshold, the monitoring device can send an alarm indication through the indicator light, the load current continues to increase. When the alarm threshold exceeds the second stage, the monitoring device alarms through the indicator light and the buzzer;
2) Leakage current alarm function can be used to measure the leakage current through the leakage current in the circuit, which is also an effective method of fire monitoring;
3) The monitoring device can monitor the opening and closing state of the circuit breaker in the circuit through two switching inputs. Besides the ACM monitoring device itself can alarm, it also has a programmable relay output, which can be one alarm, two alarms, and leakage current. Or the state of the circuit breaker is output to facilitate linkage control.
4) ACM monitoring device can have 4 ~ 20mA analog output and RS485 Modbus-RTU communication, Profibus-DP communication, easy to monitor the host computer.
4 The application of ACM in practice The ACM monitoring device is used in combination with a molded case circuit breaker. The molded case circuit breaker has two kinds of single magnetic and thermal magnetic. The single magnetic circuit breaker has only short circuit protection function and no thermal overload protection. Under the circumstances, if there is overload in the circuit, the circuit breaker will not act, and the ACM monitoring device will issue an alarm signal according to different overload levels to remind the on-site maintenance personnel to also remotely transmit to the control center. The thermal magnetic molded case circuit breaker has both short-circuit protection and thermal overload protection. At this time, the ACM monitoring device can only function as an alarm function. When the detected current reaches the set threshold, the internal relay operates.
The current transformer used by the monitoring device uses the AKH-0.66 series current transformer. If the rated current of the distribution line is 32A, and the transformer is AKH-0.66-60/5, this type of transformer has 2In range measurement and monitoring device. The maximum sustainable measurement current reaches 10A, so the device can monitor up to 4 times the overload current. The AKH-0.66L series residual current transformers are also required for applications requiring monitoring of residual current loops. In the figure above, when the current of the distribution line exceeds the alarm threshold of one stage, the relay (7, 8) is closed, the first stage of alarm output, the KA1 coil is energized, and the PGR light alarms; when the load level increases, the alarm threshold of two stages is reached. The relays (9, 10) are closed, 2 sections of alarm output, KA2 coils are powered, PG sounds alarm. When the audible and visual alarm release button is pressed or the load current decreases, the alarm state is released. The digital input can upload the circuit breaker's closing and tripping status to the background control center, and another programmable relay can be used as remote control or leakage current alarm output. Refer to the ACM overload monitoring device for details. .
5 Conclusion ACM series distribution line overload monitoring device two-stage alarm, the alarm follows the anti-time limit principle, the greater the degree of overload, the faster the alarm speed, in line with the site conditions. At the same time, the design method of the device meets the requirements of the standard well and is worthy of being used by the majority of electrical designers.
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