FUSE AUTOMATIC CHANGEOVER SYSTEM

FIELD OF INVENTION

The present invention relates to a fuse automatic changeover system. More specifically, the present invention relates to a system for automatic changeover to bypass circuit to restore fuse blown control circuit. The bypass circuit is provided with the fuse for short circuit protection. The fuse automatic changeover system provides continuous power supply to control circuits during fuse opening conditions.

BACKGROUND ART
Control circuits such as railways electrical control circuits viz., hand signal control circuit, track field changing circuits etc., fuse is provided for short circuit protection. When the fuse is blown out for momentary short circuit conditions control is lost for the connected circuits leading to failure of railways operation. Hence, it is imperative that failed control circuit is reconnected instantly to avoid any faulty or incorrect operations.

Some of the existing prior arts are as follows:

US6254434 provide a fuse bypass module, which is couplable to fuse panel to allow the bypass fuse receptacle to be coupled in parallel with a primary fuse and further allow the primary fuse to be removed without interrupting power to the load.

KR20060118835 disclosed a dual fuse system to prevent power interruption in advance, by using a subsidiary fuse when a fuse is blown out because of temporary over current state or fuse defect.

JP54091745 disclosed relates to a low voltage automatic fuse changeover device.

JP4323940 disclosed offer a backup system when a fuse is blown to reduce the service-down time by restoring the system automatically without need for a maintenance personnel to visit to a required location of the system and for replacement of a fuse when the power supply fuse to a subscriber circuit is blown due to a transitory cause in the subscriber exchange system P6076729 relates to automatic performance of changeover to a spare fuse and display it at the time of breakage of a fuse in an electric power supply device for a vehicle, a boat and the like.

DE3515773 disclosed electronic fuse monitor wherein changeover of continuous pulses for normal operation and a defect is carried out via transistors which influence the bases of the switching transistors and in addition, a light-emitting diode, which indicates a defect of the individual fuse insert.

CN2080706 disclosed relates to a fuse device for railway signal, which comprises a main cartridge fuse and a standby cartridge fuse, connected with a switching line which takes a multiple unhooking relay as the core.

The existing fuse automatic changeover systems have the following
limitations/disadvantages:

(i) Potential free relay contacts are not available. The relay contacts are required for buzzer alarming and data logging purpose. Provision of the relay is a technical challenge because, the relay should not be energized when the load is connected through by pass fuse. Existing prior arts include relays used for changeover and hence there is time delay in terms of milliseconds for changeover. Moreover, use of relays increases product size and hence retro fitment of product is not possible, (ii) Auto re-closure of mains fuse circuit is not available when the mains fuse is replaced. When the mains fuse is replaced load is not connected automatically. A user has to press a reset button to connect the load.

(iii) The number of fuse automatic changeover units required in a control room is variable. Hence, modular and retrofit product construction is required to standardize product supply.
(iv) The existing systems are bulky and separate control room is required to house the relay/contactors. Wires have to be run from mains fuse panel to control room, (v) Increased current rating in retrofit size enclosure - In the enclosure size 30 x 40 the current carrying capacity is limited to 2 amps. Current limitation is due to heat dissipation in diodes when the current is flowing through a bypass path. Accordingly, there exists a need for a system for automatic changeover to bypass circuit to restore fuse blown control circuit. Moreover, in these respects, the present invention substantially departs from the conventional concepts and designs of the prior art and in so doing it overcome other problems encountered in conventional products.

OBJECTS OF INVENTION

One or more of the problems of the conventional prior art may be overcome by various embodiments of the present invention.

The primary object of the present invention is directed to provide a fuse automatic changeover system.
It is another object of the present invention to provide a system for automatic changeover to bypass circuit to restore fuse blown control circuit.

It is another object of the present invention, wherein the bypass circuit is provided with the fuse for short circuit protection.

It is another object of the present invention, wherein the fuse automatic changeover system provides continuous power supply to control circuits during the fuse opening conditions.

It is another object of the present invention, wherein the system prevents potential free relay contacts from energizing when load current is connected through the bypass fuse.

It is another object of the present invention, wherein when the main fuse is replaced by the bypass fuse the load is automatically connected by auto re-closure of the main fuse circuit thereby obviating the need to press a reset button.

It is another object of the present invention, wherein each system replaces one main fuse available in fuse panel. The retrofit size of fuse automatic changeover system is same as space occupied by the main fuse in the fuse panel.

It is another object of the present invention, wherein available space for the fuse changeover system in the fuse panel is 30 x 40 (B X H dimensions in MM) and enclosure size required is 30x40.
It is another object of the present invention, wherein current rating/current carrying capacity is increased to 6 amps by reducing the power dissipation of current flowing through the bypass path to less than 100 miliwatts.

It is another object of the present invention, wherein the system includes one or more LEDs provided in front panel of the system to indicate the fuse status.

It is another object of the present invention, wherein the fuse automatic changeover system is compact, provided in a refit size and has a modular construction.

SUMMARY OF INVENTION

Thus according to the basic aspect of the present invention there is provided a fuse automatic changeover system for providing continuous power supply to control circuits during fuse opening conditions comprising: an enclosure;

main circuit;
bypass circuit;
one or more diodes;
one or more relays; and
one or more light emitting diodes (LEDs),
wherein the main circuit includes main fuse and one diode,
wherein the bypass circuit is connected parallel to the main circuit,
wherein the bypass circuit includes bypass fuse and two diodes,
wherein when the main fuse is closed current from power supply flows through the
main fuse and diode to load terminals,

wherein as the two diodes drop in the bypass circuit is more than one diode drop in
main circuit the current through the bypass circuit is ideally zero when the main fuse
is closed,

wherein when the main fuse is open, the current is diverted through the bypass circuit
through the diode and bypass fuse, and

wherein when the main fuse is reconnected, the load is connected to the main circuit
by auto re-closure of the main fuse thereby obviating the need to press a reset button.
It is another aspect of the present invention, wherein when the main fuse is closed, the diodes prevent the load current flowing in the bypass circuit.

It is another aspect of the present invention, wherein the diode provided in the main circuit prevents energization of the relays when the load current is flowing through the bypass fuse in the bypass circuit.

It is another aspect of the present invention, wherein the load current through the diodes is diverted through normally-closed (NC) contact of the relay.

It is another aspect of the present invention, wherein the relay connected between the main fuse and diode is a signalling relay and is provided with two-changeover potential free contacts.

It is another aspect of the present invention, wherein the changeover contacts are wired to include normally-closed (NC) contact for buzzer alarming.

It is another aspect of the present invention, wherein the changeover contacts are wired to include normally-open (NO) contact for data logger feedback.

It is another aspect of the present invention, wherein the LEDs provided on front panel of the enclosure indicates the status of the main fuse and bypass fuse.

It is another aspect of the present invention, wherein the current carrying capacity is increased to 6 amps by reducing power dissipation of current flowing through the bypass circuit to less than 100 miliwatts.

It is another aspect of the present invention, wherein time delay is in terms of microseconds for fuse changeover.

BRIEF DESCRIPTION OF THE DRAWING

Figure 1: Illustrates the circuit diagram of the system according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING FIGURE

The present invention as herein described relates to a system for automatic changeover to bypass circuit to restore fuse blown control circuit. The bypass circuit is provided with the fuse for short circuit protection. The fuse automatic changeover system provides continuous power supply to control circuits during fuse opening conditions.

Connection and working details:
The fuse automatic changeover system for providing continuous power supply to control circuits during fuse opening conditions comprising of an enclosure; main circuit; bypass circuit; one or more diodes; one or more relays; and one or more light emitting diodes (LEDs) (4, 9). The main circuit includes main fuse (1) and one diode (6). The bypass circuit is connected parallel to the main circuit and includes bypass fuse (2) and two diodes (7 and 11).

Referring to Figure 1, during normal condition current flows in the main fuse circuit i.e. through the main fuse (1) and diode (6) from the supply Vs (+) and Vs (-) to bad terminals VL (+) and VL (-). The fuse automatic changeover system connects the bypass parallel path to the open fuse path and energizes critical control circuits. When the current is flowing through the main fuse (1), the current through the bypass fuse (2) of the bypass circuit should be negligibly small. The two diodes (7 and 11) of the bypass circuit prevent current flowing in bypass path when the main fuse is closed/intact. As the two diodes drop in the bypass circuit is more than one diode drop in main circuit the current through the bypass circuit is ideally zero when the main fuse is closed/intact. When the main fuse is open the relay (12) NC contact is closed. Current through the diodes (7 andll) is diverted through the NC contacts (5 A) of relay (5). As there is no current through the diodes power dissipation in the diodes is reduced or nullified to zero watts. Reduction of power dissipation helps to increase the operating current to 6 amps. In other words, reduction of power dissipation is done by shunting the diodes (7 and 11) with NC contacts (5 A) of relay (5).

During main fuse (1) blown/open condition, the load current is diverted through bypass circuit through the diodes (7, 11) and bypass fuse (2). The relay (12) connected between the main fuse (1) and diode (6) is a signalling relay and is provided with two-changeover potential free contacts. The changeover contacts include normally-closed (NC) contact for buzzer alarming and normally-open (NO) contact for data logger feedback. Wiring is done through relay contacts to actuate the buzzer and sending data to data logger. The relay changes state when the main fuse (1) is blown/open. When the current is flowing in bypass path the relay (5) should be in OFF condition. The diode (6) provided in the main circuit prevents energization of the relay (5) when the load current is flowing through the bypass fuse (2) in the bypass circuit. When the main fuse (1) is reconnected, the load is connected to the main circuit by auto re-closure of the main fuse thereby obviating the need to press a reset button. The time delay is in terms of microseconds for fuse changeover. Moreover smaller size solid state relay is used for changeover.
Health status of the main fuse (1) and bypass fuse (2) is indicated by LEDs (4 and 9) respectively. The LEDs are provided on front panel of the enclosure. When the main fuse (1) is intact/close, LED (4) glows in green colour and is switched OFF when the main fuse is blown/open. When the bypass fuse (2) is intact/close LED (9) glows in red colour and switched OFF when the bypass fuse is blown/open.

WE CLAIM:

1. A fuse automatic changeover system for providing continuous power supply to control circuits during fuse opening conditions comprising: an enclosure; main circuit; bypass circuit; one or more diodes; one or more relays; and

one or more light emitting diodes (LEDs) (4, 9), wherein the main circuit includes main fuse (1) and one diode (6), wherein the bypass circuit is connected parallel to the main circuit, wherein the bypass circuit includes bypass fuse (2) and two diodes (7 and 11), wherein when the main fuse (1) is closed current from power supply flows through the main fuse (1) and diode (6) to load terminals,

wherein as the two diodes drop in the bypass circuit is more than one diode drop in main circuit the current through the bypass circuit is ideally zero when the main fuse is closed,

wherein when the main fuse (1) is open, the current is diverted through the bypass circuit through the diode (7,11) and bypass fuse (2), and

wherein when the main fuse (1) is reconnected, the load is connected to the main circuit by auto re-closure of the main fuse thereby obviating the need to press a reset button.

2. The fuse automatic changeover system as claimed in claim 1, wherein when the main fuse
(1) is closed, the diodes (7 and 11) prevent the load current flowing in the bypass circuit.

3. The fuse automatic changeover system as claimed in claim 1, wherein the diode (6) provided in the main circuit prevents energization of the relays (5 and 12) when the load current is flowing through the bypass fuse (2) in the bypass circuit.

4. The fuse automatic changeover system as claimed in claim 3, wherein the load current through the diodes (7 andll) is diverted through normally-closed (NC) contact (5A) of the relay (5).

5. The fuse automatic changeover system as claimed in claim 1, wherein the relay (12) connected between the main fuse (1) and diode (6) is a signalling relay and is provided with two-changeover potential free contacts.

6. The fuse automatic changeover system as claimed in claim 5, wherein the changeover contacts are wired to include normally-closed (NC) contact for buzzer alarming.

7. The fuse automatic changeover system as claimed in claim 5, wherein the changeover contacts are wired to include normally-open (NO) contact for data logger feedback.

8. The fuse automatic changeover system as claimed in claim 1, wherein the LEDs provided on front panel of the enclosure indicates the status of the main fuse (1) and bypass fuse (2).

9. The fuse automatic changeover system as claimed in anyone of claims 1 to 8, wherein the current carrying capacity is increased to 6 amps by reducing power dissipation of current flowing through the bypass circuit to less than 100 miliwatts.

10. The fuse automatic changeover system as claimed in anyone of claims 1 to 9, wherein time delay is in terms of microseconds for fuse changeover.