Surge protection device

Abstract

The invention relates to an improved surge protection device comprising a fast acting, self-restoring circuit breaker, preferably, along with surge arrestor/absorber to improve the protection and availability of the equipment which is in use with power source affected with surges/spikes which otherwise would have operated the spike/surge arrestor in-built in the equipment that would have led to its non-availability, and protection for equipment that may or may not be having in-built overcurrent, surge protection devices.

Claims

1. A surge protection device (SPD) (3) connected between an AC or DC power source and a load (4) for protecting the load (4) from surges, spikes and overvoltage conditions in the AC or DC power source, the said device comprising: power supply feed lines (1; 2); a circuit breaker line switch connected to the power supply feed lines (1; 2); a filter cum time delay circuit (14) connected so as to be downstream of the circuit breaker line switch; a fuse (9) connected downstream of filter cum time delay circuit (14); and a surge/spike arrestor (8) connected downstream of the time delay circuit (14); the circuit breaker line switch comprises a self-restoring line switch (7) connected to the power supply feed lines, and a controlled power source (6) for operating the self-restoring line switch (7); the self-restoring line switch (7) comprises a Normally Closed contact making switch (7a), an energizing coil (7b) operating the Normally Closed contact making switch (7a), and a fast electronic switch (7c) for controlling an energizing current flowing through the energizing coil (7b); the controlled power source (6) comprises a peak detector (11) for generating a trigger in response to detecting surges, spikes and overvoltage conditions in the AC or DC power source and providing the trigger to the fast electronic switch (7c); a power supply (12) for supplying the energizing current to the energizing coil (7b); and a voltage control means (10) for supplying voltage to the peak detector (11) and the power supply (12); the voltage control means (10) comprising an attenuator cum spike shunt circuit (15) connected to the power supply feed lines and a fast bridge rectifier circuit (16) connected to the attenuator cum spike shunt circuit (15).

2. The surge protection device (3) as claimed in claim 1, wherein the SPD (3) comprises of an in-built facility of earth leakage detection.

3. The surge protection device as claimed in claim 1, wherein the line switch (7) is installed in the line carrying the phase when third line for earth connection is used.

4. The surge protection device as claimed in claim 1, where the line switch (7) is installed in the line carrying the phase and fuse where possibility of earth leakage exists and/or the supply source is not isolated.

5. The surge protection device as claimed in claim 1, wherein the peak detector (11) takes lead in time as it responds to a peak instead of average through a low time delay path of attenuator-cum-spike shunt (15) which protects the fast bridge rectifier and the voltage control means.

6. The surge protection device as claimed in claim 5, wherein the peaks are attenuated far more in filter-cum-time delay (14) and only marginally in the path feeding the Peak Detector (11).

7. The surge protection device as claimed in claim 1, wherein the filter-cum-time delay (14) is a combination of inductors and capacitors.

8. The surge protection device as claimed in claim 1, wherein the power supply lines (1 and 2) to the load (4) through the line switch (7) pass through a choke (5, 5a, 5b) to cause delay to the supply passing through the line switch (7), surge arrestor and load (4) but not the feed to the controlled power source.

9. The surge protection device as claimed in claim 8 wherein the said choke (5) is a common mode choke for power supply lines (1 and 2) feeding the load.

10. The surge protection device as claimed in claim 1, wherein the power supply line (1) of the load comprises of a fuse (9) and optionally a fuse blown indicator in series on either side.

11. The surge protection device as claimed in claim 1, wherein the load (4) has an in-built surge/spike arrestor on the load side after the fuse, and voltage rating higher than the line switch trigger voltage to blow the fuse placed after the line switch and before the spike arrestor in device (3) in case of failure of line switch (7) or itself.

12. The surge protection device as claimed in claim 1 wherein the said device is provided in main and standby switchable configuration with a changeover switch.

13. The surge protection device as claimed in claim 1, wherein, the device (3) comprises of a controlled power source (6) to work as an energy source required to prevent temporary disruption of energy supply to the load/equipment during the temporary disconnection caused by the line switch (7) operation.

14. The surge protection device as claimed in claim 1, wherein an in-built facility for earth leakage detection for any or all cable conductors is connected to a device (3) independently in an isolated electrical circuit with suitable test enabling push to test switches and different colored indicators for each line to indicate whether there is earthing leakage or not in any of the lines individually.

15. The surge protection device as claimed in claim 1 wherein the device (3) can be used in railway rolling stock mounted equipment, telecommunication equipment, as well as in all general LED lighting applications.

16. The surge protection device as claimed in claim 1, wherein the peak detector (11) has a preset threshold to trigger the Line Switch (7) in time sequence which will not allow any damage to the spike/surge arrestor (8).

17. The surge protection device as claimed in claim 1, wherein the circuit breaker operation time is less than the time for which surge protector/spike arrestor can survive for a voltage and energy limit.

18. The surge protection device as claimed in claim 1, wherein the load has a self restoring line switch (7) with faster operating time than the operating time of a in-built surge/spike arrestor.

19. The surge protection device as claimed in claim 1, wherein the in-built surge/spike arrestor has lower clamping voltage than an external surge/spike arrestor, if provided, in or along the load (4).

20. The surge protection device as claimed in claim 1, wherein the said line switch (7) has a lower operating voltage than the clamping voltage of in-built surge/spike arrestor so that the voltage of in-built surge/spike arrestor does not break down and operate the fuse or external circuit breaker, and whereby the operating voltage of the line switch (7) is also lower than the clamping voltage of external surge/spike arrestor, if any.

21. A method of working of a surge protection device having output terminals (3), for protecting electrical supply systems from surges and spikes resulting from phase decomposition, wherein the operation of a line switch (7) takes a time lead over the surge reaching the output terminals of the SPD, wherein a filter-cum-time delay (14) which is a combination of inductor(s) and capacitor(s) and a controlled power source desists the surge from building up in time to pass through the filter towards the surge protection device (3) output and the delay is further increased as the surge passes over a spike/surge arrestor wherein the operating design of the line switch (7) is well below the upper limit of a normal operating range of the input supply so that at connection of input supply in time sequence a power supply (12) to operate the line switch (7a,b,c) gets ready even before the supply that reaches the load (4) has reached its normal state and is maintained near about the maximum voltage to operate the line switch at its fastest, a power supply (12) to operate the line switch upon trigger from the peak detector (11) such that a peak detector (11) takes lead in time as it responds to a peak instead of average and that also through a low time delay path of attenuator-cum-spike shunt (15) which protects a fast bridge rectifier (16), wherein the peak detector (11) has a preset threshold to trigger the line switch (7) in time sequence which will not allow any damage to the spike/surge arrestor (8) or allow any violation of an input condition of the load to pass through.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 shows the device (3) connection with power source line 1 and line 2 and load

(2) FIG. 2 shows the device (3) connection with power source and load with optional power storage (10.1)

(3) FIG. 3 shows some of the components of device (3)

(4) FIGS. 4 & 5 shows the controlled power source components and configurations of choke

(5) FIG. 6 shows some internal details of the components and a configuration of controlled power source of SPD device (3)

(6) FIG. 7 shows working connection details of device (3) inclusive of earth leakage detector with optional Push to ON switch to detect, when required, earth leakage on either line individually.

(7) FIG. 8 shows the working connection details of main and standby device (3)

DETAILED DESCRIPTION OF THE INVENTION

(8) The present invention provides an improved surge protection device (SPD) for an electronic equipment comprising a self-restoring circuit breaker preferably along with surge arrestor/absorber to improve the availability of the equipment in use with power source affected with surges/spikes.

(9) The circuit breaker can be a fast acting relay or any means having a NO/NC contact(s) made to operate through the voltage control means such that it opens before the internal and/or external surge/spike arrestor(s), if the system breakdown voltages are crossed. It not only protects the equipment but also the surge absorbers/spike arrestors like MOV or other devices being used in the system so that their operating life is substantially enhanced or not affected.

(10) FIG. 1 shows input supply line 1 and 2 passing through the external optional choke (needed more for AC supply circuits), both the lines then connecting to the SPD(3), having a controlled power source (6) to detect the condition and operate the line switch (7) which can switch line 2 to disconnect the equipment under unsafe conditions. The SPD having a surge arrestor (8) after the line switch (7) towards the load (4) side whose operating voltage is higher than the line switch (7) when operated to disconnect the load (4) but preferably lower than the surge/spike arrestor, if any, provided in the load. In the event, the spike/surge arrestor in the SPD operates, which would normally be in the event line switch or its required operation has failed, it disconnects the fuse (9) (optional) or the external circuit breaker. Lines 1 and 2 pass out of the SPD and connect to the load.

(11) FIG. 2 shows provision of extra energy storage on the equipment/load side where in-operation caused due to short term disconnection is to be avoided and the equipment is also to be protected from damage. Such stored energy can also be incorporated in the load where it is critical only to keep the core part in operation, and when incorporated in conjunction or as a part of SPD it can be permanently connected when fed by the same energy source or it can get connected through a Normally Open (NO) contact when the disconnection takes place as per the requirement.

(12) FIGS. 3 and 4 shows an SPD with inbuilt choke. The choke wherever used for AC supply system could be optionally a common mode choke.

(13) FIG. 5 shows the details of the Controlled Power Source (6) which could optionally have peak voltage detector (11) to operate the line switch with minimum loss of time, voltage control means (10) to detect the surge operating point and a power supply (12) to operate the line switch. The power supply may also be used to maintain a storage energy means to prevent loss of information or inoperative state between disconnection and re-connection caused by line switch (7) while protecting the equipment/load.

(14) FIG. 6 shows the operation of the line switch (7a,b,c)

(15) FIG. 7 shows a schematic flow diagram of the improved surge protection device (3) with electrically isolated earth leakage tester unit. Each line is connected for leakage test through separate push to test switches and any leakage current with earth connection when detected will light up the particular line's designated indicator. The indicator for leakage test ON is separate. Upon release of the push-to-test switch the earth leakage detector gets isolated. Input and output lines are connected to the SPD through connector or switch as per usage needs. The input power may be disconnected when this test is conducted. The output connection can be switchable to select two different lines, in the event earth fault is detected in one pair the operation can be shifted to the other pair.

(16) FIG. 8 shows one example of the main and standby configurations with optional earth leakage detector. Here the input can be switched to standby SPD in case of fault in main SPD. Further, in another configuration the output lines can also be switchable in case if earth fault in one pair the operation can be shifted to the other output pair

(17) One of the objectives of the invention is that the line switch should operate well before any damage is caused to the SPD or the load equipment due to voltage surges or spikes in the input supply, which may then result in the equipment to become in-operational due to SPD or equipment failure.

(18) There are two configurations of SPD, one where the load equipment and its input protection internal details are available and/or input protection and input power/internal supply details are available and the other where specific internal details are not available.

(19) The second configuration is shown in FIG. 2a where also the method by which the operation of the line switch (7a,b,c) leads in time to cut-off the line before the quantum surge reaching the spike/surge arrestor (8) or the output terminals of SPD to load reaches a harmful state.

(20) The fast operation of the protection device/line switch is achieved by placing the components of the controlled power source in the SPD in a manner that operation of the line switch when required takes a time lead over the surge reaching the output terminals of the SPD. The filter-cum-time delay a combination of inductor(s) and capacitor(s) desists the surge from building up in time to pass through it towards the SPD output and the delay is further increased as the surge passes over the spike/surge arrestor due the inherent properties of the same. The operating design of the line switch (7) is well below the upper limit of the normal operating range of the input supply. Thus, at switch on/connection of input supply in time sequence the energy storage/power supply (12) to operate the line switch (7a, b, c) gets ready even before the supply reaching the Load has reached its normal state. Thus, the power supply (12) is armed to operate the line switch (7) upon trigger from the peak detector (11). The peak detector (11) takes lead in time as it responds to the peak instead of average and that also through a low time delay path of attenuator-cum-spike shunt (15) which protects the voltage control means which can be a simple fast device bridge rectifier. Thus, whereas the peaks are attenuated far more in filter-cum-time delay (14) but only marginally in the path feeding the peak detector. The peak detector has a preset threshold to trigger the line switch in time sequence which will not allow any damage to the spike/surge arrestor (8) or allow anything violating the input condition of the load to pass through the fast operation (operation time 20 ms from the appearance of Power Supply) electromechanical relay of suitable rating contacts, from a fully pre-energised energy tank during normal operation for immediate operation of the relay typically operating it in few milliseconds. Provision of additional energy source unit (10) results in further augmenting the protection.

(21) The circuit breaker operation time is less than the time for which surge protector/spike arrestor can survive for the voltage and energy limit, thus before the time in which the breakdown of the surge/spike arrestor would occur the line switch would disconnect the surge energy flowing in. Thus, two conditions are met: a. the surge protection in the SPD optionally provided prevents the breakdown of the surge protection which may be provided in the load equipment b. the self restoring line switch prevents the breakdown both of the surge protection provided optionally in the SPD and the surge protection provided in the load equipment and maintains the availability of the load equipment despite the surges on the power supply feeding it, which otherwise would have damaged the load equipment in the absence of SPD

(22) A table (TABLE 1) showing the necessary parameters for a railway application employing the surge protection device of the present invention is provided herein below:

(23) TABLE-US-00001 TABLE 1 max Energy surge Line Peak absorption Surge peak Switch Line Line Surge High Supply Equipment (2 ms) Dissipation Current Response Switch Switch Suppressor Voltage Supply Upper Load Wmax Capacity Capacity Time Operating Restoring Clamping SPD Rating Type Limit Limit (KW) (J) KV (J) (8/20 s) (ms) Voltage Voltage voltage(8/20 s) Rating (V) 60 VDC 78 1 106 0.016 106 6500 A <20 mili- 85 5 70 5 250 1500 second 10 106 0.016 106 6500 A <20 mili- 85 5 70 5 250 1500 second 60 VAC 78 1 106 0.016 106 6500 A <20 mili- 85 5 70 5 250 1500 second 10 106 0.016 106 6500 A <20 mili- 85 5 70 5 250 1500 second 110 VDC 143 1 155 0.009 155 6500 A <20 mili- 158 5 140 5 300 1500 second 10 155 0.009 155 6500 A <20 mili- 158 5 140 5 300 1500 second 110 VAC 143 1 155 0.009 155 6500 A <20 mili- 158 5 140 5 300 1500 second 10 155 0.009 155 6500 A <20 mili- 158 5 140 5 300 1500 second 220 VDC 286 1 330 0.045 330 6500 A <20 mili- 315 10 280 10 775 1500 second 10 330 0.045 330 6500 A <20 mili- 315 10 280 10 775 1500 second 220 VAC 286 1 330 0.045 330 6500 A <20 mili- 315 10 280 10 775 1500 second 10 330 0.045 330 6500 A <20 mili- 315 10 280 10 775 1500 second

(24) The controlled power source used to operate the line switch (7) constitutes voltage control means (10) which may constitute a fast bridge rectifier (16) to ensure unipolarfeed to operate the line switch through peak detector, a attenuator-cum-spike shunt (15) to ensure adequate protection to the voltage control means without causing much time delay wherein peak detector (11) ensures fast operation on the negative or positive (made unidirectional/unipolar) rising of the surge in either direction beyond the normal operating range, a power supply (12) quickly armed to a value of upper limit to operate the line switch (7) in fastest mode without damaging it.

(25) The applications wherein the surge protection device may be used are in railway rolling stock mounted equipment, telecommunication equipment, as well as in all general LED lighting applications.

(26) Typical operation parameters that are utilized is provided in Table 2 below:

(27) TABLE-US-00002 TABLE 2 (Operational Parameters) S. No. Functional Requirement Rating 1. Nominal System Supply 110 110 220 220 Voltage VAC VDC VAC VDC 2. Surge Absorber operating Up to 20% above Equipment voltage (SAV) Upper Rated Voltage limit or 10% lower to the MOV/arrestor Voltage in equipment, whichever is lower 3 Line Switch Response Time <20 ms 4. Surge Absorber Energy .sup.>100 Joules Dissipation 5. Arrestor Surge Current >6500 A Withstand Capability 6. Line Switch Operating 10% lower to SAV Voltage (SOV) 7. Line Switch Restore Voltage 5 to 10% lower to SOV 8. Surge Attenuator type Common Mode 9. Earth Leakage indicator line 1 RED (Optional see 12 below) 10. Earth Leakage indicator Line 2 Yellow (Optional see 12 below)

(28) One of the main embodiment of the present invention is to provide a surge protection device (SPD) (3) with fast acting self-restoring circuit breaker along with surge arrestor/absorber (8), the said device (3) connected between an AC or DC power source and a load (4) for protecting the electrical supply feed given to the load (4) from surges, spikes and overvoltage conditions resulting from phase decomposition, induction or any other factor, comprising: one power supply feed line (1) connected to the load (4) second power supply feed line (2) connected to load (4) after passing through a line switch (7) and is connected to the load (4) under normal operating conditions, and optionally an in-built facility for earth leakage detection, wherein, the said line switch (7) operates to disconnect the line (2) from the load (4) under high voltage condition caused by surges and/or any other means to disconnect the load (4) and any surge/spike arrestor (8) down the line before its operating parameters are exceeded and restores the connection when voltage input is in normal range, wherein the said surge protection device comprises of in-built controlled power source to operate the line switch (7) with self-restoring circuit breaker such that the controlled power source used to operate the line switch (7) constitutes voltage control means (10) which constitutes a fast bridge rectifier (16) to ensure unipolar feed to operate the line switch (7) through peak detector (11), a attenuator-cum-spike shunt (15) to ensure adequate protection to the voltage control means without causing much time delay, the said peak detector (11) to ensures fast operation on the negative or positive (made unidirectional/unipolar) rising of the surge in either direction beyond the normal operating range, a filter cum time delay (14) desisting the surge from building up in time to pass through it towards the SPD output and the delay is further increased as the surge passes over the spike/surge arrestor (8), a power supply (12) quickly armed to a value of upper limit to operate the line switch (7) in fastest mode without damaging it.

(29) Yet another embodiment of the present invention is to provide a surge protection device (3), wherein the in-built facility of earth leakage detection is preferably provided in device (3) connecting to loads through a cable going into the field to feed a distantly placed load (4), where the cable can be exposed to earth leakage.

(30) Yet still another embodiment of the present invention is to provide a surge protection device (3), wherein the line switch (7) is installed in the line carrying the phase when third line for earth connection is used.

(31) Yet still another embodiment of the present invention is to provide a surge protection device (3), wherein the line switch (7) is installed in the line carrying the phase where possibility of earth leakage exists and/or the supply source is not isolated.

(32) Still yet another embodiment of the present invention is to provide a surge protection device (3), wherein the peak detector (11) takes lead in time as it responds to the peak instead of average and that also through a low time delay path of attenuator-cum-spike shunt (15) which protects the fast device bridge rectifier (16).

(33) Yet still another embodiment of the present invention is to provide a surge protection device (3), wherein the peaks are attenuated far more in filter-cum-time delay (14) and only marginally in the path feeding the Peak Detector (11).

(34) Yet another embodiment of the present invention is to provide a surge protection device (3), wherein the peak detector (11) has a preset threshold to trigger the line switch (7) in time sequence which will not allow any damage to the spike/surge arrestor (8).

(35) Still another embodiment of the present invention is to provide a surge protection device (3), wherein the circuit breaker operation time is less than the time for which surge protector/spike arrestor can survive for the voltage and energy limit.

(36) Another embodiment of the present invention is to provide a surge protection device (3), wherein the filter-cum-time delay (14) is a combination of inductors and capacitors.

(37) Still another embodiment of the present invention is to provide a surge protection device (3), wherein the voltage control means has an attenuator-cum-spike shunt (15), spike arrestor (8), bridge rectifier (16), and series parallel diodes in bridge rectifier (16) alone or in any combination thereof.

(38) Another embodiment of the present invention is to provide a surge protection device (3), wherein the power supply lines (1 and 2) pass through a choke (5, 5a, 5b).

(39) Still another embodiment of the present invention is to provide a surge protection device (3), wherein the said choke (5) is a common mode choke for power supply lines (1 and 2).

(40) Another embodiment of the present invention is to provide a surge protection device (3), wherein the said voltage control means has a fast bridge rectifier (16) and attenuator-cum-spike shunt (15) to increase the upper voltage operating range of the line switch (7).

(41) Yet another embodiment of the present invention is to provide a surge protection device (3), wherein the said line switch (7) is a fast operating relay with at least one NO/NC contact.

(42) Still another embodiment of the present invention is to provide a surge protection device (3), wherein the power supply line (1) of the load comprises of a fuse (9) and optionally a fuse blown indicator in series on either side.

(43) Another embodiment of the present invention is to provide a surge protection device (3), wherein the load (4) has an in-built surge/spike arrestor on the load side after the fuse, and voltage rating higher than the line switch trigger voltage to blow the fuse in device (3) in case of failure of line switch (7) or itself.

(44) Still another embodiment of the present invention is to provide a surge protection device (3), wherein the load has a line switch (7) with faster operating time than the operating time of the in-built surge/spike arrestor.

(45) Yet another embodiment of the present invention is to provide a surge protection device (3), wherein the in-built surge/spike arrestor has lower damping voltage than the external surge/spike arrestor, if provided, in or along the load (4).

(46) Another embodiment of the present invention is to provide a surge protection device (3), wherein the said line switch (7) has a lower operating voltage than the damping voltage of in-built surge/spike arrestor so that the voltage of in-built surge/spike arrestor does not break down and operate the fuse or external circuit breaker, and whereby the operating voltage of the line switch (7) is also lower than the damping voltage of external surge/spike arrestor, if any.

(47) Still another embodiment of the present invention is to provide a surge protection device (3), wherein the said device (3) is provided in main and standby switchable configuration of the same or different configuration preferably with a changeover switch.

(48) Yet still another embodiment of the present invention is to provide a surge protection device (3), wherein, optionally, a controlled power source (6) is used to work as an energy source required to prevent temporary disruption of energy supply to the load/equipment during the temporary disconnection caused by the line switch (7) operation.

(49) Still another embodiment of the present invention is to provide a surge protection device (3) wherein the in-built facility for earth leakage detection for any or all cable conductors is connected to the device (3) independently in an isolated electrical circuit with suitable test enabling push to test switches and preferably different colored indicators for each line to indicate whether there is earthing leakage or not in any of the lines individually.

(50) Yet still another embodiment of the present invention is to provide a surge protection device (3), wherein the device (3) can be employed in railway rolling stock mounted equipment, telecommunication equipment, as well as in all general LED lighting applications.

(51) Another embodiment of the present invention is to provide a method of working of a surge protection device (3), for protecting electrical supply systems from surges and spikes resulting from phase decomposition, wherein the operation of the line switch (7) takes a time lead over the surge reaching the output terminals of the SPD, wherein a filter-cum-time delay (14) which is a combination of inductor(s) and capacitor(s) and the controlled power source desists the surge from building up in time to pass through the filter towards the device (3) output and the delay is further increased as the surge passes over the spike/surge arrestor wherein the operating design of the line switch (7) is well below the upper limit of the normal operating range of the input supply so that at connection of input supply in time sequence the power supply (12) to operate the line switch (7a,b,c) gets ready even before the supply that reaches the load (4) has reached its normal state, a power supply (12) to operate the line switch upon trigger from the peak detector (11) such that the peak detector (11) takes lead in time as it responds to the peak instead of average and that also through a low time delay path of attenuator-cum-spike shunt (15) which protects the fast bridge rectifier (16), wherein the peak detector (11) has a preset threshold to trigger the line switch (7) in time sequence which will not allow any damage to the spike/surge arrestor (8) or allow any violation of the input condition of the load to pass through.

(52) Although, the present invention has been described with reference to features, it will be apparent to those skilled in the art that this description is only a preferred embodiment and does not limit the scope of the present invention. Variations and modifications are possible without departing from the scope and spirit of the invention disclosed/described herein and are intended to be encompassed therein.