The power “shock power†generally refers to the short circuit fault of the power grid caused by a lightning strike, a short circuit to the ground, a power plant failure, and other internal and external faults, causing the power supply voltage to fluctuate greatly in a short time, and even a short power failure for several seconds.
With the development of the power grid, system capacity, and the continuous expansion of the scale of power usage, the impact of the Akira power phenomenon is increasing and the scope of spread is becoming wider. Due to the increasing scale of modern industrial and mining enterprises, the duration of Akira is relatively short, but the impact on production is enormous. Instantaneous voltage fluctuations will cause hundreds of motor trips and equipment shutdown. After the grid voltage recovers, the motor will not be able to resume operation on its own, causing continuous production process disturbances and possible serious production and equipment accidents. For large devices, due to the large number of devices, it takes a long time to recover manually, and panic is prone to operational errors; for some unattended field devices, the recovery time is longer. For a continuous production facility such as petroleum, chemicals, and pesticides, a series of losses such as safety, environmental protection, waste products, waste of raw materials, reduced production, and low profitability are very large. According to the analysis of the operating characteristics of the AC motor, the short-term power failure has a very small effect on the motor speed. After the grid voltage is restored to normal, it is completely feasible to immediately resume the motor operation, and the starting impulse current is small (close to the rated current), thus ensuring the The safety and continuity of important power load operation.
In addition, as the degree of factory automation increases, the secondary circuit of the motor becomes more and more complicated. In addition to the basic thermal protection, the control of the pump of the chemical plant generally has three places of control: switchboard control, on-site control, and control room control. The control loop is more and more complex, with many circuit nodes and a very high failure rate. Moreover, due to the conventional secondary control loop stop and thermal protection using normally closed contacts in series, each control terminal influences each other, and line or equipment failures are likely to cause total loss of control. The inspection and processing time is longer and the quality of maintenance personnel is also proposed. Higher requirements.
In order to solve the Akira electricity problem, at present, there are special anti-sweeping electrical relays and anti-sweeping electrical alternating current contactors in foreign countries, but their expensive manufacturing prices have deterred the average user. In order to solve these problems in the control of electrical equipment, we specially organized and developed an intelligent motor controller that not only solved the problem of anti-shudder, but also solved the more complex problems of the secondary circuit of the motor. After two years of trial and error, Widely praised by users.
First, design ideas:
1. Anti-swing electrical function: When the grid voltage is ultra-low and the power-off time is less than the setting time, as long as the power grid returns to normal, the motor will automatically return to its original operating state. When the power-off exceeds the setting time, the motor cannot recover by itself, and manual operation must be performed Start processing.
2. The control circuit is simplified and the control terminal is infinitely expanded: The control terminals of the design start, stop, and protection all use the normally open contact and connection method, and the main contactor does not need to access the self-protection contact. With such a large number of controls, the complexity of the secondary circuit is greatly reduced, and control terminals of the same function can be connected in parallel. The common line is the middle line, which can be shared when multiple points are controlled remotely, which can reduce the line cost. During the operation of the motor, there is no loop current in the control button circuit, and the control buttons do not affect each other. Even if a single control button fails to close, it will not affect the motor operation. In special cases, the live button can be checked during the running of the motor. Reduced system failure rates and maintenance downtime.
3, to prevent the protection of misuse: the traditional series of protection nodes to the parallel connection, can prevent non-power protection products in the control loop prone to repetitive actions, expand the application of non-power protection products.
Second, the factory application situation and the solution to the problem:
In the past two years or more, we have conducted long-term application tests in power plants and chemical plants. In early 2008, we designed and applied the device in the automatic control system of the glyphosate production plant we undertook. There are more than 180 systems in the system. In the long-term operation of the motor, the quality of the equipment itself has stood the test and the user has given a high evaluation.
During the initial trial of the trial, some controllers will malfunction and relays will not be released. After repeated inspection of the design of the logic circuit, component selection and installation wiring, etc., did not find the incorrect place. After analysis, in a single-phase AC control loop, when one end of the relay coil is connected to the neutral line and the other end is connected to a long cable core, the induced voltage of the long cable core forms a path through the relay coil to the neutral line. Generally, the AC contactor is driven due to the driving energy. The problem of high consumption is not significant, and the return of the relay can be affected when the return voltage of the relay is low. After the actual test of the control loop, it was found that in the motor control loop, due to the influence of the parasitic capacitance of the cable, the induced voltage on the control line reaches about 100V. If there are multiple loops in the multi-core control cable and different loops are used, The power supply is out of phase and the induced voltage will be higher. After repeated tests, we reversed the polarity of the power supply of the control circuit and connected one end of the relay to the phase wire so that both ends of the relay coil were equipotential (phase-to-ground voltages are all phase voltages), and the induced voltage no longer functions. Thoroughly solved the problem of induced voltage interference.
In addition, it has been found that when used in conjunction with a DCS or PLC system, occasional self-locking occurs. After an in-depth study of the circuit, it was found that the operation cycle of the DCS and the PLC is relatively short (milliseconds), and in some cases the motor is started after a false start, the control The system quickly issued a protection and shutdown action. Because the action cycle is short, the controller's charging time is too short, resulting in insufficient energy release to form a self-locking. This forced the release of measures to improve the circuit to solve this problem.
Third, product industrial design:
When the components are selected, Omron self-retaining relays and Izumi relays are used. The power consumption of the circuit is low, less than 0.3W, and the product reliability is high.
In order to facilitate the use and maintenance of users, we have repeatedly improved, designed a variety of humanized model products to meet the different needs of different users:
DQZ-IIa is a rail-mounted type in the cabinet. The wiring uses pluggable terminals. It can quickly replace the equipment without disconnecting wires. This product is suitable for the user's existing equipment for technological transformation.
DQZ-IIb is a disk-mounting type, which adopts 48*96 standard panel mounted case, which can be assembled. The rear terminal board is screwed. The plug-in type movement is selected to facilitate the user's quick replacement. This product is suitable for new installations. When the switchboard is designed, the controller is directly installed on the disk. The start and stop buttons and the operation indicator are all integrated into the controller. The disk does not need to be installed. This simplifies the wiring.
In addition, the corresponding models DQZ-IIaP and DQZ-IIbP have been specially designed for high-end users to use with DCS or PLC.
Fourth, application areas:
The device can be widely applied to the pump control of process continuous production devices such as chemical, petrochemical, pesticide, fertilizer, and medicine, and the pump control of power plants, thermal power, and water supply devices at low cost. It is especially suitable for unattended pumping stations such as oil extraction and water supply, equipment room control, and occasions that have high requirements for continuous operation, serious downtime, and electrical equipment that uses multiple control.
With the development of the power grid, system capacity, and the continuous expansion of the scale of power usage, the impact of the Akira power phenomenon is increasing and the scope of spread is becoming wider. Due to the increasing scale of modern industrial and mining enterprises, the duration of Akira is relatively short, but the impact on production is enormous. Instantaneous voltage fluctuations will cause hundreds of motor trips and equipment shutdown. After the grid voltage recovers, the motor will not be able to resume operation on its own, causing continuous production process disturbances and possible serious production and equipment accidents. For large devices, due to the large number of devices, it takes a long time to recover manually, and panic is prone to operational errors; for some unattended field devices, the recovery time is longer. For a continuous production facility such as petroleum, chemicals, and pesticides, a series of losses such as safety, environmental protection, waste products, waste of raw materials, reduced production, and low profitability are very large. According to the analysis of the operating characteristics of the AC motor, the short-term power failure has a very small effect on the motor speed. After the grid voltage is restored to normal, it is completely feasible to immediately resume the motor operation, and the starting impulse current is small (close to the rated current), thus ensuring the The safety and continuity of important power load operation.
In addition, as the degree of factory automation increases, the secondary circuit of the motor becomes more and more complicated. In addition to the basic thermal protection, the control of the pump of the chemical plant generally has three places of control: switchboard control, on-site control, and control room control. The control loop is more and more complex, with many circuit nodes and a very high failure rate. Moreover, due to the conventional secondary control loop stop and thermal protection using normally closed contacts in series, each control terminal influences each other, and line or equipment failures are likely to cause total loss of control. The inspection and processing time is longer and the quality of maintenance personnel is also proposed. Higher requirements.
In order to solve the Akira electricity problem, at present, there are special anti-sweeping electrical relays and anti-sweeping electrical alternating current contactors in foreign countries, but their expensive manufacturing prices have deterred the average user. In order to solve these problems in the control of electrical equipment, we specially organized and developed an intelligent motor controller that not only solved the problem of anti-shudder, but also solved the more complex problems of the secondary circuit of the motor. After two years of trial and error, Widely praised by users.
First, design ideas:
1. Anti-swing electrical function: When the grid voltage is ultra-low and the power-off time is less than the setting time, as long as the power grid returns to normal, the motor will automatically return to its original operating state. When the power-off exceeds the setting time, the motor cannot recover by itself, and manual operation must be performed Start processing.
2. The control circuit is simplified and the control terminal is infinitely expanded: The control terminals of the design start, stop, and protection all use the normally open contact and connection method, and the main contactor does not need to access the self-protection contact. With such a large number of controls, the complexity of the secondary circuit is greatly reduced, and control terminals of the same function can be connected in parallel. The common line is the middle line, which can be shared when multiple points are controlled remotely, which can reduce the line cost. During the operation of the motor, there is no loop current in the control button circuit, and the control buttons do not affect each other. Even if a single control button fails to close, it will not affect the motor operation. In special cases, the live button can be checked during the running of the motor. Reduced system failure rates and maintenance downtime.
3, to prevent the protection of misuse: the traditional series of protection nodes to the parallel connection, can prevent non-power protection products in the control loop prone to repetitive actions, expand the application of non-power protection products.
Second, the factory application situation and the solution to the problem:
In the past two years or more, we have conducted long-term application tests in power plants and chemical plants. In early 2008, we designed and applied the device in the automatic control system of the glyphosate production plant we undertook. There are more than 180 systems in the system. In the long-term operation of the motor, the quality of the equipment itself has stood the test and the user has given a high evaluation.
During the initial trial of the trial, some controllers will malfunction and relays will not be released. After repeated inspection of the design of the logic circuit, component selection and installation wiring, etc., did not find the incorrect place. After analysis, in a single-phase AC control loop, when one end of the relay coil is connected to the neutral line and the other end is connected to a long cable core, the induced voltage of the long cable core forms a path through the relay coil to the neutral line. Generally, the AC contactor is driven due to the driving energy. The problem of high consumption is not significant, and the return of the relay can be affected when the return voltage of the relay is low. After the actual test of the control loop, it was found that in the motor control loop, due to the influence of the parasitic capacitance of the cable, the induced voltage on the control line reaches about 100V. If there are multiple loops in the multi-core control cable and different loops are used, The power supply is out of phase and the induced voltage will be higher. After repeated tests, we reversed the polarity of the power supply of the control circuit and connected one end of the relay to the phase wire so that both ends of the relay coil were equipotential (phase-to-ground voltages are all phase voltages), and the induced voltage no longer functions. Thoroughly solved the problem of induced voltage interference.
In addition, it has been found that when used in conjunction with a DCS or PLC system, occasional self-locking occurs. After an in-depth study of the circuit, it was found that the operation cycle of the DCS and the PLC is relatively short (milliseconds), and in some cases the motor is started after a false start, the control The system quickly issued a protection and shutdown action. Because the action cycle is short, the controller's charging time is too short, resulting in insufficient energy release to form a self-locking. This forced the release of measures to improve the circuit to solve this problem.
Third, product industrial design:
When the components are selected, Omron self-retaining relays and Izumi relays are used. The power consumption of the circuit is low, less than 0.3W, and the product reliability is high.
In order to facilitate the use and maintenance of users, we have repeatedly improved, designed a variety of humanized model products to meet the different needs of different users:
DQZ-IIa is a rail-mounted type in the cabinet. The wiring uses pluggable terminals. It can quickly replace the equipment without disconnecting wires. This product is suitable for the user's existing equipment for technological transformation.
DQZ-IIb is a disk-mounting type, which adopts 48*96 standard panel mounted case, which can be assembled. The rear terminal board is screwed. The plug-in type movement is selected to facilitate the user's quick replacement. This product is suitable for new installations. When the switchboard is designed, the controller is directly installed on the disk. The start and stop buttons and the operation indicator are all integrated into the controller. The disk does not need to be installed. This simplifies the wiring.
In addition, the corresponding models DQZ-IIaP and DQZ-IIbP have been specially designed for high-end users to use with DCS or PLC.
Fourth, application areas:
The device can be widely applied to the pump control of process continuous production devices such as chemical, petrochemical, pesticide, fertilizer, and medicine, and the pump control of power plants, thermal power, and water supply devices at low cost. It is especially suitable for unattended pumping stations such as oil extraction and water supply, equipment room control, and occasions that have high requirements for continuous operation, serious downtime, and electrical equipment that uses multiple control.