POWER SYSTEM SWITCHING SIMULATOR
FIELD OF THE INVENTION
[0001] This invention relates to simulators that creates field conditions like voltage / load fluctuations at a fast rate.
BACKGROUND OF THE INVENTION
[0002] During the working of an ac electrical system, three loads come into picture. These three standard loads are namely the inductive, capacitive and resistive loads. The three standard loads must be monitored and their effect on the working of any electrical system must be identified. When the ac electrical system operates, these loads combine with one another or overlap with each other, and affect the system having these loads. Whenever there is a fluctuation in the load, the working behavior of the system changes.
[0003] For example, when there is switching of the inductive load there will be high spikes and other noises. All kind of noise and spikes gets overlapped and enters into the ac electrical system such as a meter. This changes the behavior of the meter and therefore functioning of the meter might vary. To prevent the variations in the meter and the proper functioning of the meter, analog timers are generally used. Analog timers are used for load changeover and control.
[0004] These timers are periodically switched on and off in order to prevent overlapping of these three loads.
[0005] Conventional load timers basically function in ON and OFF operations. The three periodic timers therefore only ON and OFF their respective load. Normally the load gets switched ON and runs for a period of time and then switches OFF to prevent any noise being created and picked up by the system.
[0006] However, in live wire condition, various noises are being generated continuously at a very fast rate. Hence these three timers are generally unable to switch

between the loads at a very fast rate i.e. < 1 s. if a user switches ON the capacitor at a fast rate, charging and discharging will be more and therefore its effect will be there on the meter. Whenever fast switching is present, more spikes are generated on the line where the meter might be connected. Hence the meter is affected and changes in its behavior.
[0007] Hence, there is a need, to enable a user identify the field condition in order to prevent its effect on an ac electrical system.
SUMMARY OF THE INVENTION
[0008] An object of the present invention is to generate field conditions during operation of an ac electrical system.
[0009] Another object of the present invention is to enable a user understand the effect of field condintions such as voltage failure, voltage fluctuation and switching at fast rate, load changeover, and load switching at fast rate on the ac electrical system.
[0010] Accordingly, a power system switching simulator is disclosed herein, that generates field conditions during operation of an ac electrical system. In one embodimet herein, the simulator comprises a controller having atleast one predefined test sequence. The test sequence may be input by a user with the help of a plurality of input switches. Each switch may be connected to the controller for facilitating a user to input the desired test sequence to the controller.
[0011] Further, a plurality of relays may be electrically connected to the controller. The user-defined test sequences may comprise inputs including Chattering count, Chattering interval. Load ON Time, and Load Overlap Time and based on the said test sequence inputs, the controller may generate various control-signals that control the ON/OFF operation of the relays. The ON/OFF operation of the relays thus generate field conditions during operation of the ac electrical system and enabling the user to investigate the operational behavior of the electrical system in said field conditions.
[0012] In one embodiemnt herein a display may be connected to the controller for displaying data at input/output stages of the electrical system. Further, a relay-driver may

also be connected between the controller and the relays for driving the relays by providing control-signals of the controller to the relays.
[0013] Other objects, features and advantages of the invention will be apparent from the drawings, and from the detailed description that follows below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Reference will be made to embodiments of the invention, examples of which may be illustrated in the accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in the context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.
[0015] Figure 1 is a block diagram of the power system-switching simulator according to an embodiment of this invention.
[0016] Figure 2 is a block diagram of a typical power supply,
[0017] Figure 3 is a flow chart illustrating the working of the power system-switching simulator according to an embodiment of this invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] In the following description, specific details are set forth in order to provide an understanding of the invention. However, it will be apparent that one skilled in the art will recognize that embodiments of the present invention, some of which are described below, may be incorporated into a number of different systems and devices. Block diagrams are illustrative of exemplary embodiments of the invention and are meant to avoid obscuring the invention. Furthermore, connections between components within the figures are not intended to be limited to direct connections. Rather, data between these components and modules may be modified, re-formatted or otherwise changed by intermediary components and modules.
[0019] Reference will be now made to figures wherein Figure 1 depicts the basic structure of the power system-switching simulator. The simulator 100 may be used in the

operational environment of any ac electrical system (not shown) that is prone to get affected due to any fluctuations in the ac parameters of said electrical system. Said ac electrical system may include any kind of commercial/industrial appliances such as any KWH meter (Kilo-Watt-Hour Meter) that work on the three phase power supply.
[0020] According to the present invention, the application of the simulator 100 in the operational environment of any ac electrical system generates field conditions and thus enables a user to understand the effect of field condintions on the ac electrical system. The field condition may include the conditions of voltage failure, voltage fluctuation and switching at fast rate, load changeover, and load switching at fast rate.
[0021] As shown in Figure 1, the switching simulator comprises a controller 101 having an internal memory 101a for storing atleast one predefined test sequence data. The internal memory 101a may be programmable non-volatile memory such as EEPROM (Electrically Erasable Programmable Read Only Memory) that stores the test sequence even during the power failure. The controller 101 may be connected to a plurality of switches 102. These switches 102 may be used to send inputs to the controller 101. Preferably, four switches may be used to enable a user to feed inputs. When the user feeds input to the controller 101, he/she basically customizes the predefined test sequence data. In an embodiment of the present invention, the test sequence data comprises inputs including Chattering Count, Chattering Interval, Load ON Time, and Load Overlap Time, These four inputs are fed by using the four switches as explained above.
[0022] Also, a plurality of relays 103 are electrically connected to the controller 101. The relays perform ON/OFF operations at the command of the controller 101. The controller 101 gives command to these relays 103 by sending control signals which are based on the said test sequence inputs. The controller 101 thus generates control-signals to control the ON/OFF operation of the relays 103 thereby generating field conditions during operation of the ac electrical system and enabling the user to investigate the operational behavior of the electrical system in said field condifions. A relay-driver 107 is connected between the controller 101 and the relays 103. The relay driver 103 drives the relays 103 by providing control-signals from the controller 101 to the relays 103. The

relay driver operates by receiving dc voltage from the controller which receives operating voltage from a power supply 107 as shown. The power supply 107 receives ac voltage from mains and outputs 5V/24V dc voltage to the controller 101 for its operation. The power supply 107 receives 240 volts ac from the mains at a cycle of 50 Hz.
[0023] A display 104 for displaying data at input/output stages of the electrical system may also be connected as shown. The display is preferably an LCD display capable of displaying the readings at a good resolution. For adjusting the resolution of the display device 104, an adjustment 105 such as a potentiometer may be used. Further, a 4 MHz crystal timer 106 may be used to provide a clock for operations of the controller 107. Preferably, the said controller 101 may be a PIC (Programmable Intelligent microcontroller) capable of being reprogrammed by the user.
[0024] Figure 2 shows the block diagram of the power supply 107 that comprises 240 ac supply 201, a step down transformer 202 to bring down the 240 volts of the mains to a low voltage of about 0-10 Volts for generating 5 V dc voltage. Whereas, the transformer may step down the mains voltage to about 0-25 Volts for generating 24 V dc voltage. A rectifier and a filter block 203 may be connected at the output of the transformer 202 in order to change the ac voltage to dc voltage and also to remove the ripples. The final output block 204 gives the required 12V/24V dc voltage to the controller and thereafter to the relay.
[0025] Figure 3 is a flow chart illustrating the working of the power system-switching simulator. The simulator starts its operation by performing the process of Controllers Ports Initializafion 301. After initializing the ports the simulator requests 303 the user to clear the memory. Upon receiving the instructions from the user, the controller clears 302 its internal memory. Thereafter the simulator displays 304 programming modes along with a request from the user to select 'Continue' or 'Skip[0026] If the user selects 'Continue', he/she is requested 305 to enter the four inputs through the four switches. The four inputs include Chattering Count, Chattering Interval, Load ON Time, and Load Overlap Time that decide the ON/OFF operation of

the relays after being processed by the controller. As soon as these four inputs are entered, the Switching task (ON/OFF of the relays) at infinite loop is performed 308 using the test sequence inputs i.e. ON Time, Overlap Time, Chattering Count and Chattering interval.
[0027] In case the user selects 'Skip he/she is provided with a memory readings of previous settings on the display 306. Thereafter, and in the case of user not selecting 'Continue' or 'Skip' the internal memory of the controller is read 307 for any relevant data. When the user does not selects 'Continue' or 'Skip', the controller waits for 1 minute before reading 307 the internal memory of the controller for any relevant data.
[0028] If relevant data is found in the memory, then the Switching task (ON/OFF of the relays) at infinite loop is performed 308 using the test sequence inputs i.e. ON Time, Overlap Time, Chattering Count and Chattering interval.
[0029] If no relevant data is found, the simulator goes 309 to its predefined or the default setting (1 min, ON time) and performs the Switching task (ON/OFF of the relays) at infinite loop.
[0030] The present invention thus provides a PIC based simulator that is small in size (compact) and easy to handle. Since the whole operation is controlled by PIC, accuracy is maintained. The LCD display enables the user to visualize the timing on which the loads are working. The EEPROM enable the permanent storage of the values so that even if the power fails the values will remain there in the memory. The controller can be programmed many times according to user convenience,
[0031] Following are the list of test sequences and settings for the simulator described above:
Sequence -1:
• R & V Switching using Chattering count and Interval or time,
• Resistive ON using Load ON Time
• V Switching using Chattering count and Interval or time.

• LC overlap ON using Load overlap time,
• C & V Switching using Chattering count and Interval or time.
• Capacitive ON using Load ON Time
• V Switching using Chattering count and Interval or time,
• RL overlap ON using Load overlap time.
• Inductive ON using Load ON Time
• V Switching using Chattering count and Interval or time,
• Inductive ON using Load ON Time
• RC & V Switching using Chattering count and Interval or time.
• RC overlap ON using Load overlap time.
• RCL overlap ON using Load overlap time,
• V Switching using Chattering count and Interval or time.
• No Load using Load overlap time.
Sequence-2:
• Resistive ON using Load ON Time
• Capacitive ON using Load ON Time
• Inductive ON using Load ON Time
• No Load using Load overlap time.
Defauh setting:
• Resistive(R) ON for Imin

• Capacitive(C) ON for 1min
• Inductive(L) ON for 1min
• System Shutdown for 1min
[0032] Various specific embodiments of this invention provide a power System switching simulator. Although various modifications that would be obvious to a person skilled in the art are possible, the invention is limited to the claims claimed herein.

We claim:
1. A power system switching simulator for generating field conditions during
operation of an ac electrical system, the simulator comprising:
a controller having atleast one predefined test sequence data;
a plurality of input switches, each connected to the controller for enabling a user to customize a predefined test sequence data within the controller;
a plurality of relays electrically connected to the controller; and
a display for displaying data at input/output stages of the electrical system;
wherein the test sequence data comprises inputs including at least one of Chattering Count, Chattering Interval, Load ON Time, and Load Overlap Time, wherein based on the said test sequence inputs, the controller generates control-signals to control the ON/OFF operation of the relays thereby generating field conditions during operation of the ac electrical system so as to enable the user to investigate the operational behavior of the electrical system in predetermined field conditions.
2. The simulator according to claim 1, wherein field condition includes voltage failure, voltage fluctuation and switching at fast rate, load changeover, and load switching at fast rate.
3. The simulator according to claim 1. wherein the controller is a programmable intelligent micro controller,
4. The simulator according to claim 1, wherein the controller comprises an internal programmable non-volatile memory for storing data of the test sequence.
5. The simulator according to claim 1, wherein the Chattering count input is set at about 1-20 count limits.
6. The simulator according to claim 1, wherein the Chattering interval input is set at about 20 milliseconds to about 50 milliseconds limits.

7. The simulator according to claim 1, wherein the Load ON Time input is set at
about 1 minute to about 60 minutes limits.
8. The simulator according to claim 1, wherein the Load Overlap Time input is set at
about 1 minute to about 60 minutes limits.
9. The simulator according to claim 1, wherein a relay-driver is connected between
the controller and the relays for driving the relays by providing control-signals of the
controller to the relays.