WO2007037609A1

WO2007037609A1 - Centrally controlled automatic power saving apparatus

Info

Publication number: WO2007037609A1
Application number: PCT/KR2006/003815
Authority: WO
Inventors: Jeong-Do Lim
Original assignee: Jeong-Do Lim
Priority date: 2005-09-29
Filing date: 2006-09-26
Publication date: 2007-04-05
Also published as: KR200403816Y1

Abstract

This invention relates to an automatic power saving apparatus using a PLC and comprises, a PLC (Programmable logic controller) that compiles the input information and the output information on an electric power system and controls the electric power system to maintain the best operating condition; a converter that converts the information which said PLC requires into values which said PLC can recognize and supplies; a wireless modem to transmit the alarm condition of the power saving apparatus to an external system operator immediately; a touch panel that displays the operating condition of the power saving apparatus on the screen so that the system operator can confirm, and by which the system operator inputs orders to said PLC for the best operation of the system; a programming tool to make programs which are necessary for said PLC to control the system; a mutual inductive reactor which is a linear low voltage device that improves the quality of electricity by removing the harmonics and noises that are generated at the power system, can change the tap automatically when required with numbers of taps, and has sufficient capacity to achieve the system optimization; a monitoring computer that monitors and records the operating condition of the power saving apparatus in real time and controls it remotely; and a communication card that converts all conditions and operating orders which said monitoring computer requires in order to said PLC can recognize and is used attached on said PLC.

Description

CENTRALLY CONTROLLED AUTOMATIC POWER SAVING

APPARATUS

TECHNICAL FIELD This invention relates to an automatic power saving apparatus, particularly a centrally controlled power saving apparatus which is embodied by a PLC (Programmable logic controller) and operates fully automatically.

BACKGROUND ART All of the products available at the existing power saving apparatus market adopt an artificial and uniform way of controlling voltage, and they are operated ignoring all the elements like the region, the time zone, or the sorts of load.

In this situation, the loads working at the lower part of the power saving apparatus can face a severe electric power environment at a moment. Therefore the power saving apparatus which was installed with a lot of funds even shortens the machine's life, and causes higher electronic bills in some cases.

The reasons of the gradual decrease of the power saving apparatus at the market although there are a lot of related products and supports can be that no maker has solved the above-mentioned problems yet, and there is almost no investments in the technical development areas.

As for Korea which totally depends on the imported petroleum, we should continuously complement the problems despite said negative elements, and try to develop and apply products that meet the user's environment. Meanwhile, power saving is generally defined as reducing the consumption of electric power by enhancing the efficiency of electric devices or eliminating unnecessary electricity consumption by controlling the electric power. General power saving apparatus is an assistant that encourages people's spirit of power saving, and the reactor which is the main element of the power saving apparatus improves the quality of electricity by removing the harmonics and noises that are generated frequently at the power system. Figure 1 illustrates a block diagram of general power saving apparatus.

In general, electric devices or equipment consume more electricity than actual amount of necessary work because they are designed to have 1.3-1.5 times as much as margin considering the safety rate which is necessary when they operate, and the decline of efficiency. A power saving apparatus is a reliable energy saving apparatus which saves valuable electric energy by controlling voltage in the range of normal operation of the equipment and improving power factor with such margin and lengthens the life of electric devices or equipment. In Korea, it is prescribed that the standard voltage supplied from the power supplying corporation should be 233 V ~ 207V which is within ±13V(±6%) of the standard voltage 220V, and in case that the standard voltage is 380V, within ±38V(±10%). The supplied voltage is regionally different, and generally the voltage of the termination is maintained and managed to have deviation within the range of said standard voltage, while the electricity is transmitted by the raised voltage considering the drop of voltage on the wiring. And the output voltage of the neighboring transformer is 230V.

In Korea, electric devices using 220V or 380V should be operated normally in the range of ±10% of the voltage, and the efficiency described in the specifications should be acquired according to the KS (Korean Industrial Standard), so they can be operated normally.

Under these circumstances, the problems of the existing power saving apparatus are as follows: Firstly, when the first installation is done, the operator chooses a power saving tap after he checks the input voltage, and starts the power saving operation with that power saving tap.

Secondly, though the input voltage is changed, the tap is not changed unless the operator changes it. Thirdly, though the output voltage causes a fatal operating condition because of the changed input voltage, the power saving apparatus operates defenselessly.

Fourthly, even though the reactor and electric field equipment in the power saving apparatus are affected by the continuous condition, they are repeatedly overheated because there is no safety device to control that. So the apparatus shortens its lifetime by itself, and the investors sustain damages in the end.

For the above reason, the market of the power saving apparatus which should carry out the national subject gives a negative impression. As a result, rat races are only at the small market of small-sized or household products, instead of going to the huge market.

TECHNICAL PROBLEM

The purpose of this invention is to provide an efficient and economical power saving apparatus that can solve the above defects of the prior arts.

Other purposes and merits of this invention will be clear upon reading the detailed explanation and referring to the attached drawings.

TECHNICAL SOLUTION This invention relates to an automatic power saving apparatus using a PLC and comprises, a PLC (Programmable logic controller) that compiles the input information and the output information on an electric power system and controls the electric power system to maintain the best operating condition; a converter that converts the information which said PLC requires into values which said PLC can recognize and supplies; a wireless modem to transmit the alarm condition of the power saving apparatus to an external system operator immediately; a touch panel that displays the operating condition of the power saving apparatus on the screen so that the system operator can confirm, and by which the system operator inputs orders to said PLC for the best operation of the system; a programming tool to make programs which are necessary for said PLC to control the system; a mutual inductive reactor which is a linear low voltage device that improves the quality of electricity by removing the harmonics and noises that are generated at the power system, can change the tap automatically when required with numbers of taps, and has sufficient capacity to achieve the system optimization; a monitoring computer that monitors and records the operating condition of the power saving apparatus in real time and controls it remotely; and a communication card that converts all conditions and operating orders which said monitoring computer requires in order to said PLC can recognize and is used attached on said PLC. In this invention, said converter is a transducer or a power analyzer.

In this invention, said PLC at least comprises a CPU, a main memory unit, an input unit, an output unit, a calculation unit, an auxiliary memory unit, peripheral devices, and an analog card.

In this invention, it is preferable that said information which said PLC requires at least comprises input-output voltage, current, power factor, frequency, electric power, and abnormal signal.

In this invention, it is preferable that said PLC output unit has proper tap selection function, mode change function, alarm function, and interlock function.

In this invention, it is preferable that the screen on which said touch panel displays at least comprises a main screen to monitor the process, equipment monitoring screen, alarm monitoring screen, and set value input screen; said main screen displays input voltage, output voltage, output current, frequency, power factor, operating mode, power saving mode, expected power saving rate, capacity of apparatus, operating rate of power saving apparatus, and provides means of an emergency stop; said equipment monitoring screen displays input voltage, output voltage, output current for each phase of 3 -phase electric power system, and displays frequency, operating mode, and expected power saving rate; said alarm monitoring screen displays alarm starting time, alarm contents, and alarm releasing time; and the operator sets the output voltage for each phase with '+', '-', 'confirm' buttons in said set value input screen, and operation mode and operation selection are automatically set as a default value.

In this invention, it is preferable that said communication card uses at least one of the communication methods among RS-232C, RS-422, Ethernet, and RS-485. In this invention, it is preferable that the voltage is controlled considering the region, time zone, and the sort of load, and the capacity of said reactor is selected under 1.3 times of necessary amount of work in order to achieve the optimization in the range of normal operation.

In this invention, it is preferable that the secondary output voltage corresponding to the primary input variance of said reactor can be automatically controlled, the voltage in proportion to the drop of voltage according to the increase of the secondary load of said reactor can be automatically controlled, keeping record about operating information and outputting daily report and monthly report is possible, and unmanned operation by remote control system is possible. This invention preferably further comprises a bypass device that automatically changes to electricity supply mode of general electricity incorporation in an overload, over voltage, or under voltage condition, and returns to the power saving mode again if it is monitored that the overload, over voltage, or under voltage condition is finished after monitoring the load condition at all times.

ADVANTAGEOUS EFFECTS

The expected effects of the power saving apparatus according to this invention are summarily reliability, stability, economical efficiency, and convenience. More detailed effects are as follows: Firstly, the secondary output voltage corresponding to the primary input variance can be automatically controlled.

Secondly, the voltage in proportion to the drop of voltage by the increase of the secondary load can be automatically controlled.

Thirdly, it is possible to construct the screen with which the user can easily monitor the operating information of the power saving apparatus.

Fourthly, operation of the power saving apparatus and confirmation of the operating condition are achieved visually by the monitoring screen. And the power saving apparatus is convenient because it is structured as an artificial intelligence type.

Fifthly, keeping the record of operating information and outputting daily report and monthly report is possible. Sixthly, unmanned operation by remote control system is possible.

Seventhly, operation without an interruption of electric power is possible by the automatic bypass function so that the reliability of power system is improved.

Eighthly, it is possible to protect the circuit completely by setting the lowest secondary operating voltage so that stability is guaranteed. Ninthly, since the stabilized power saving rate is guaranteed and an optimization of recovery period in comparison with the investment is possible, it is economical.

DESCRIPTION OF DRAWINGS

Figure 1 illustrates a block diagram indicating the structure of a general power saving apparatus.

Figure 2 illustrates a block diagram indicating the structure of a PLC used in this invention.

Figure 3 illustrates an embodiment of a power saving apparatus according to this invention. Figure 4 illustrates a block diagram indicating the structure of a power saving apparatus according to this invention.

Figure 5 illustrates an embodiment of a touch panel screen of a power saving apparatus according to this invention.

Figure 6 illustrates an internal structure of a power saving apparatus according to this invention.

Figure 7 illustrates an external structure of a power saving apparatus according to this invention.

Figure 8 illustrates a control panel of a power saving apparatus according to this invention.

BEST MODE

It has become possible to stand the same electric power as the type of general transformer with 1/10 capacity of it, and to control the voltage and current without deforming or damaging AC power source, by using a mutual inductive reactor, which is a peculiar linear low voltage device, in general power saving apparatus.

The mutual inductive reactor used in this invention is divided into the primary voltage coil (primary winding) wound to the toroidal core and the secondary current coil (excitation winding), the voltage coil has voltage control tap of several steps, the secondary current coil has the capacity of rated current and wound in the opposite direction to the primary coil, and the ends of the voltage coil and the current coil are connected in series in order to act as a serial reactor. So if the current flows to the secondary coil in the opposite direction when the voltage lowered at the primary voltage coil is impressed to the reactor, current is induced to the voltage coil by the mutual induction. So the current at the voltage coil is raised, and the raised current is supplied to the output of the secondary current coil connected to the voltage coil. In this way, feedback current is added to the current that flows at the output of the secondary coil and the added current is supplied to the load, while the current at the input goes down. This is the basic principle of a mutual inductive reactor type power saving apparatus.

As for the power saving effect by the mutual induction, the more the voltage is lowered, the more the power saving rate is improved, but the degree of lowering should be decided according to the reactor efficiency and the load condition.

Now we make an explanation about the PLC used in this invention. The PLC (100) used in this invention is widely used in the general industrial automation process including the factory automation. As shown in Figure 2, the PLC (100) comprises a CPU (10), a main memory unit (20), an input unit (30), an output unit (40), a calculation unit (50), an auxiliary memory unit (60), and peripheral devices (70).

The input unit (30) is the most basic element of the PLC and comprises the things which can take actions of the types that the PLC can recognize. There are things which can be read as digital values such as operating buttons and sensors, and can be read as analog values such as water levels and temperatures.

The output unit (40) is realized as a form of operating external devices among the values calculated at the PLC, and there are things which send digital values such as opening and closing solenoid valves or starting and stopping motors, and send analog values such as control valves.

The calculation unit(50) has a function that the PLC processes various works and a part among them that calculates numerical formulas considering the processing speed of the CPU sends the processed values to the CPU by separate works.

The PLC repeats the work of reading the program logic in order, processing after reading the input value, and outputting in order. In this case, the main memory unit (20) memorizes the input value. PLC has several kinds of classes per products maker and there are a lot of PLC makers. All makers are providing their own PLC programming tools they developed. So only the programming tool of their own maker can be used in order to construct and program the PLC system of the corresponding maker. Among these various elements of the PLC, there are many differences in memory capacity according to the class. Like this, the main memory unit has characteristics given to each PLC class, so the auxiliary memory unit (60) is used for smoother function of the processor.

The peripheral devices (70) from several major makers make it possible to communicate each other by agreements among the makers under competitions of the market resulting from the diversity of the PLC makers. There can be a problem of disconnection of the whole line through the communication because of the different makers per each equipment. For this reason, users may unify the whole equipment into the products of one maker, which can cause uniformity of the market. For fear of that, each of the makers is seeking coexistence by making it possible to communicate through the PLC. Moreover, the function of communication gets more powerful because of the development of the computer equipment. As a result, the role of the peripheral devices (70) is more and more increasing.

Figure 3 conceptually illustrates an embodiment of a power saving apparatus used in this invention. Assuming that the power saving apparatus is used in an office, the power saving apparatus is connected to the network through the PLC system, and the computer in the office, telephone, cellular phone, the computer and printer in the briefing room are also connected. In this case, by connecting the power saving apparatus of this invention to each electrical appliance in the office through the network, efficient power saving can be achieved. Figure 4 illustrates a block diagram indicating the structure of a power saving apparatus according to this invention. Now referencing Figure 4, we explain about all elements and the principle of the operation of the power saving apparatus according to this invention.

The power saving apparatus (1000) of this invention at least comprises a PLC (100); a transducer or power analyzer (200); a wireless modem (300); a touch panel (400); a programming tool (500); a reactor (600); and a communication card (700). The PLC (100) in this invention is a key device in operating the power saving apparatus (1000) automatically, which compiles the input information and output information on an electric power system and controls the electric power system to maintain the most ideal operating condition.

The transducer (A, V, KW, PF, HZ) or power analyzer (200) in this invention provides information required by the PLC (100), and converts various kinds of condition values such as input-output voltage, input-output current, electric power, power factor, and frequency into analog (4-2OmA, or 0-1 OV) values for the PLC to recognize. As previously explained about PLC, the PLC interprets input values by digital values (0 or 1), analog values, or by the way of communication, and in order to read the periodical and continuous values that are indicated by the amount, the PLC should recognize analog values. For this, the analog card (80) is prepared in the PLC.

Said values provide the CPU (10) of the PLC (100) with the information through the transducer (200) and the analog card (80).

The wireless modem (300) is one of the most important devices which can transmit the alarm condition has arisen at the power saving apparatus (1000) to the operator outside immediately. Using a wireless communication means in the power saving apparatus (1000) of this invention is practically inappropriate though it is possible. Because there are problems of frequency band, communication fee, and related regulations, operating the system using radio frequency is not practical.

A monitoring computer (800) is needed to monitor and record the operating condition of the power saving apparatus (1000) in real time and controls it remotely, and a communication card (RS-232C, RS-422, or Ethernet card) (700) that is used attached on the PLC is needed to convert all the conditions and the operating orders that this computer requires in order to said PLC can recognize.

In this case, a proper communication card (700) should be selected, RS-232C or RS- 422 called as a serial communication is mainly used for a short distance in the same operation area, and Ethernet type using existing internet line is applied for a long distance. In case that operation of numbers of power saving apparatus or computers is required, RS-485 called as parallel communication is used. Since all of said communication methods are international standards, any type of PLC can have a suitable communication card.

After installing the power saving apparatus at first, the operator should give proper orders to the PLC of the power saving apparatus. Even for a simple changing to the power saving mode, the PLC should recognize it, and for this, we use the means of so called touch panel (400).

The previous power saving apparatus (1000) is operated with suitable substrate, and for the means of operating selection, switch, selection button, lamp, and the like are used. This is the type that lets the operator simply select safety mode or power saving mode, choose the proper tap, and confirm the result with a lamp. So unless the operator operates it again, the power saving apparatus remains the first operating condition. In this case, even though the operation of the power saving apparatus is changed from power saving mode to safety mode for any reason, the operator cannot recognize the change without seeing the lamp, does not know the reason, and hesitates to change into the power saving mode again.

In this invention, all functions are displayed in the monitor of touch panel (400) as pictures and only the most necessary function is selected, and controlled properly by the PLC (100).

Operating condition of the power saving apparatus (1000), various data, error and alarm history are displayed as characters or graphs in the touch panel (400). So the touch panel (400) can be said that a small computer which makes the operator easily recognize the operation history and cause of the power saving apparatus (1000) defects, and current operating condition.

Figure 5 illustrates an embodiment of a touch panel screen of a power saving apparatus according to this invention. Top left-hand screen illustrates a main screen to monitor the process. Input voltage, output voltage, output current, frequency, power factor, operating mode, expected power saving rate, operating rate of power saving apparatus, capacity of apparatus are displayed in the main screen.

Top right-hand screen in Figure 5 illustrates a screen to monitor the equipment. Input voltage, output voltage, output current, frequency per each phase (R, S, T phase) are displayed, operating mode, expected power saving rate are also displayed in this screen.

Bottom left-hand screen in Figure 5 illustrates an alarm monitoring screen. Alarm starting time, alarm contents, and alarm releasing time are displayed in this screen.

Bottom left-hand screen in Figure 5 illustrates a set value input screen. In this screen, output voltage per each phase can be controlled and the set value is controlled with '+', '- ', 'confirm' buttons. Operation mode' and 'operation selection' are automatically set as a default value.

The screen that the touch panel provides is the one among the main screens to monitor the process, equipment monitoring screen, alarm monitoring screen, and set value input screen. A means for an emergency stop is also comprised.

PLC is an apparatus that repeats mechanical operation, so various processes like how to operate the apparatus, which function to use, which complementary apparatus to put in, how to decide operating order are programmed in a language that the PLC (100) can recognize and stored in the PLC (100), and the processes are decided by this program. A programming tool (500) is needed for this and it is comprised of related software and hardware like a notebook computer. The most important element here is a programmer's program, and one of the greatest advantages of the PLC (100) is that it can accommodate everything flexibly. Necessary functions should be put in the substrate when the substrate is designed in the previous power saving apparatus, so we could not use a function that is not prepared in the substrate. It has a competitive power considering the price, but the power saving apparatus having various characteristics according to the capacity and the characteristics of the substrate that is applied uniformly because of the load characteristics only burden with the machine. So all power saving apparatus makers were eager to put various functions in the substrate at first, but now they do not apply except some indispensable functions.

The key element in the power saving apparatus (1000) is the reactor (600), and the most important things in the operation of the power saving apparatus (1000) are the flexible tap change and the sufficient capacity selection. If the tap change is not automatically accomplished according to the input/output voltage change, even the power saving apparatus can be dangerous to both the lower load and the power saving apparatus itself.

However, though the importance of the tap change was highly emphasized in the past power saving apparatus even using as many as 5 taps, the current related industries are using compulsory 1 : 1 drop of voltage type instead of using taps because evils by the manual operation has threatened the apparatus.

But this invention solved these problems by adopting an automatic tap change function. So the danger followed by the manual tap changing has disappeared. As a result, a safe operation became possible even for large capacity power saving apparatus.

Meanwhile, one of these simplex communication, half-duplex communication, or full-duplex communication can be used as the communication method in this invention.

The simplex communication is a communication method that information flow is always transmitted to one direction. The information cannot be transmitted in an opposite direction in this method.

The half-duplex communication cannot transmit information flow to both directions simultaneously by using one line of cable, but can transmit to both directions at a distance of time.

The full-duplex communication can transmit and receive information flow simultaneously by using two lines of cable. It is the most advanced method, technically.

Generally, data transmission methods can be divided into 2 as follows considering the speed, the stability, and the economical efficiency when transmitting data by binary (binary digit comprised of 0 and 1). Serial transmission method transmits data by one bit each through one cable. Transmitting speed is slow, but installation cost is low and the software is simple. RS- 232C, RS-422, RS-485, and the like correspond to this.

Parallel transmission method is used at printers and the like and transmits data by one byte. A transmitting speed and an accuracy of data are high, but an installation cost increases by geometric progression if the transmission distance gets longer.

Asynchronous Communication is a transmission method adjusting synchronism by one character each when transmitting serially. Synchronizing signal (clock signal, etc.) is not transmitted at this time. Character code is sent by attaching start bit in front of one character, and stop bit is attached at the end of the character.

Protocol means the communication rule set in advance between a transmitting part and a receiving part of information in order to give and receive efficient and reliable information between computers and terminals without errors. Generally, it prescribes call establishment, connection, structure of the form of message exchange, retransmitting to the error message, circuit reverse procedure, character synchronism between terminals, and the like.

To explain BPS (Bits Per Second) and CPS (Characters Per Second), BPS means a unit of transmission rate indicating how many bits are transmitted per 1 second, CPS means how many characters are transmitted per 1 second. Since 1 character is 1 byte (8 bit) in general, CPS is the number of bytes that can be transmitted per second.

Node means the connecting joint of data at the tree structure of network, generally a network is comprised of numbers of nodes. Packet is a compound word of package and bucket, and used in packet exchange system that transmits information divided by packet. Packet means a part of the transmitted data split into a predetermined length, having a header indicating the address (exchange number, etc.) of the other side.

Port is a part of data processing equipment that receives or sends data from a remote terminal in data communication. It means RS-232C or RS-422 port in Cnet serial communication.

RS-232C is an interface to connect a modem with a terminal, or a modem with a computer. It is a serial communication protocol established by EIA according to the recommendation of CCITT. It is used not only to connect with a modem, but also to connect directly with a null modem. The defect of it is that transmission distance is short and only 1 :1 communication is possible. The protocols that overcame the defects are RS-422 and RS-485. RS-422/RS-485 are one of the serial communication protocols, have a longer transmission distance compared with RS-232C, and 1:N connection is possible. The difference between the two protocols is that while RS-422 uses 4 signal lines as TX(+), TX(-), RX(+), RX(-), RS-485 can transmit and receive through the same signal line because it has 2 signal lines (+), (-). For this reason, RS-422 performs a full-duplex type communication, and RS-422 performs a half-duplex type communication. The half-duplex communication is the type of communication that can communicate in both directions but it is impossible to transmit and receive at the same time, RS-485 belongs to it. Since transmission and receipt are achieved through one communication line, multi-drop type of communication that numbers of stations communicate through one signal line is much used. As this type of communication uses one signal line, there can be data losses by a data collision in case that numbers of stations transmit at the same time. So since numbers of stations cannot transmit at the same time, this type of communication is called half-duplex communication.

The full-duplex communication is a communication type that transmitting and receiving in both directions at the same time, RS-232C and RS-422 belong to it. As transmitting line and receiving line are separated, transmitting and receiving between a master station and a corresponding station are possible at the same time without data collision, so this type is called full-duplex communication.

Meanwhile, serial transmission has a danger of transmitting distorted signal because of unwanted noises in the transmission line. BBC (Block Check Character) is data for receiving part to be able to judge if the signal is normal or distorted. The receiving part itself computes BBC using the data which came to the front end of BBC, compares it with received BBC, and can judge whether the signal is normal or not.

Frame is comprised of sent or received data in a fixed form in data communication. It comprises additional information like segment (exchange number, order, parameter according to the order), control character (ENQ, ACK, EOT, ETX) for synchronization, parity for detecting errors, and BBC.

Figure 6 illustrates an internal structure of a power saving apparatus according to this invention, Figure 7 illustrates an external structure of a power saving apparatus according to this invention, arid Figure 8 illustrates a control panel of a power saving apparatus according to this invention.

Meanwhile, this invention has a bypass function. This function is already a general art in most power saving apparatus. So we will explain this briefly. The bypass device is prepared to prevent the destruction of the power saving apparatus and to avoid a power failure and to supply a safe power to customers in case that momentarily or suddenly more load power than the capacity of the power saving apparatus is needed. In this way, the bypass function is protecting the power saving apparatus and preventing the power failure by making current or voltage not to be inputted or outputted through the power saving apparatus and stopping the operation of the power saving apparatus momentarily, and changing to non power saving mode (for instance, direct power using mode supplied by a general electricity incorporation like KEPCO) at once, when more power than the capacity of the power saving apparatus is needed momentarily or momentary overload, over voltage, or under voltage condition is happened.

In the previous manual power saving apparatus, when the bypass function is operated because of overload, over voltage, or under voltage condition, the convert switch has to be switched to the power saving mode manually in order to function as a power saving apparatus, and in order to confirm if the power saving condition is being maintained and if the bypass function is being operated, the operator has to monitor the inside of the power saving apparatus very often and has to operate the apparatus manually.

But in this invention, though the bypass function is operated because of the overload, over voltage, or under voltage condition, if the condition disappears, it is sensed and the operating mode is again returned to the power saving mode automatically. So in this invention, the operator does not have to monitor the inside of the power saving apparatus or confirm if the bypass function is being operated very often, as in the previous apparatus. For example, this function can be achieved by installing a monitoring device of overload, over voltage, or under voltage parallel to the load. This invention may be modified and embodied in various forms, and it has been described and illustrated herein with reference to a specific embodiment thereof. However, it should be understood that this invention is not limited to the particular form as described above, and that this invention includes all modifications, equivalents and substitutes within the spirits and scope of this invention as defined in the "claims" attached hereto.

INDUSTRIAL APPLICABILITY

This invention is to provide an efficient and economical power saving apparatus that can solve the defects of the previous power saving apparatus, and can be applied in the electric power industries.

Claims

1. An automatic power saving apparatus using a PLC and comprising: a PLC (Programmable logic controller) that compiles the input information and the output information on an electric power system and controls the electric power system to maintain the best operating condition; a converter that converts the information which said PLC requires into values which said PLC can recognize and supplies; a wireless modem to transmit the alarm condition of the power saving apparatus to an external system operator immediately; a touch panel that displays the operating condition of the power saving apparatus on the screen so that the system operator can confirm, and by which the system operator inputs orders to said PLC for the best operation of the system; a programming tool to make programs which are necessary for said PLC to control the system; a mutual inductive reactor which is a linear low voltage device that improves the quality of electricity by removing the harmonics and noises that are generated at the power system, can change the tap automatically when required with numbers of taps, and has sufficient capacity to achieve the system optimization; a monitoring computer that monitors and records the operating condition of the power saving apparatus in real time and controls it remotely; and a communication card that converts all conditions and operating orders which said monitoring computer requires in order to said PLC can recognize and is used attached on said PLC.

2. An automatic power saving apparatus using a PLC as set forth in claim 1, characterized by that said converter is a transducer or a power analyzer.

3. An automatic power saving apparatus using a PLC as set forth in claim 1, characterized by that said PLC at least comprises a CPU, a main memory unit, an input unit, an output unit, a calculation unit, an auxiliary memory unit, peripheral devices, and an analog card.

4. An automatic power saving apparatus using a PLC as set forth in claim 1, characterized by that said information which said PLC requires at least comprises input-output voltage, current, power factor, frequency, electric power, and abnormal signal.

5. An automatic power saving apparatus using a PLC as set forth in claim 1, characterized by that said PLC output unit has proper tap selection function, mode change function, alarm function, and interlock function.

6. An automatic power saving apparatus using a PLC as set forth in claim 1, characterized by that the screen on which said touch panel displays at least comprises a main screen to monitor the process, equipment monitoring screen, alarm monitoring screen, and set value input screen; said main screen displays input voltage, output voltage, output current, frequency, power factor, operating mode, power saving mode, expected power saving rate, capacity of apparatus, operating rate of power saving apparatus, and provides means of an emergency stop; said equipment monitoring screen displays input voltage, output voltage, output current for each phase of 3-phase electric power system, and displays frequency, operating mode, and expected power saving rate; said alarm monitoring screen displays alarm starting time, alarm contents, and alarm releasing time; and the operator sets the output voltage for each phase with '+', '-', 'confirm' buttons in said set value input screen, and operation mode and operation selection are automatically set as a default value.

7. An automatic power saving apparatus using a PLC as set forth in claim 1, characterized by that said communication card uses at least one of the communication methods among RS-232C, RS-422, Ethernet, and RS-485.

8. An automatic power saving apparatus using a PLC as set forth in claim 1, characterized by that the voltage is controlled considering the region, time zone, and the sort of load, and the capacity of said reactor is selected under 1.3 times of necessary amount of work in order to achieve the optimization in the range of normal operation.

9. An automatic power saving apparatus using a PLC as set forth in claim 1, characterized by that the secondary output voltage corresponding to the primary input variance of said reactor can be automatically controlled, the voltage in proportion to the drop of voltage according to the increase of the secondary load of said reactor can be automatically controlled, keeping record about operating information and outputting daily report and monthly report is possible, and unmanned operation by remote control system is possible.

10. An automatic power saving apparatus using a PLC as set forth in claim 1, characterized by that said power saving apparatus further comprises a bypass device that automatically changes to electricity supply mode of general electricity incorporation in an overload, over voltage, or under voltage condition, and returns to the power saving mode again if it is monitored that the overload, over voltage, or under voltage condition is finished after monitoring the load condition at all times.