GB2268341A - Electric fuse - Google Patents

Abstract

A self-diagnostic illuminating electric fuse comprises a hollow glass tube 1 with metal contacts 2 and 3 at both ends which are interconnected with a fuse wire 4 lying inside the hollow tube 1. Current travels from one end e.g. 2 to the other e.g. 3 through fuse wire 4 and thus by-passes a parallel arrangement of a bulb 5 and a resistor 6. When there is a break in the fuse wire 4, Current passes instead through bulb 5 and resistor 6. The bulb is thereby illuminated but the amount of current flowing is very small owing to the high value of resistor 6. <IMAGE>

Description

SELF DIAGNOSTIC ILLUMINATI.NG ELECTRIC FUSE This invention relates to an electrical fuse cartridge that has an in-built micro lamp which lights up when the fuse wire burns out.

Cartridge fuses come in several .sizes and ratings1 the most widely used is in the form of a hollow glass tube with metal contacts on either end, both ends connected to each other with a fuse wire placed in the hollow tube. The newer types currently used in motor cars are flat and-made of plastic encompassing a fuse wire connected to two contact ends which plug in an appropriate holder.

According to the present invention, the fuse cartridge contains not only the fuse wire but also a miniature electric bulb of a compatible voltage but of a much lower wattage than the fuse wire itself. The two electrical connections of the bulb are connected in a parall-el circuit via a resistor to the fuse wire joining the two contact ends of the fuse.

When the fuse wire is intact it allows the currentto pass through it but when the +use blows out and the fuse wire breaks, current cannot pass through the fuse wire, it starts to travel through the miniature bulb which lights up indicating a blown out fuse. For safety, the miniature bulb used is of a very low rating, lOOmA or less in conjunction with a high -value resistor and operating on a very tiny amount of current, ensures the blockage of the normal level of current passing through to the circuit.

wath conventional. fuses- it is d-i.fficult to ascertain the condition of a ,fuse without physically checking it by means of an appropriate testing --device unless .the,broken fuse wire is visible to the naked eye and this is not possible if the cartridge is opaque.

With this illuminating feature, a blown out fuse is easily detected. This feature will not only be welcomed in the domestic or motor car use, but prove a great boon in industry aircraft, ships, and communicati.on where early detection of a faulty circuit could save money and probably lives.

A specific embodiment of the invention described by way of example with reference to the accompanying drawing in which Figure 1. shows in perspective a fuse cartridge where the hollow glass tube 1 has two metal contacts 2 and 3 at each end which are connected to each other by means of a fuse wire 4 placed inside the hollow glass tube 1. Along side this fuse wire 4 i.s a miniature bulb 5 which has one of .its wires attached to one of the mental contacts 3 and the other wire to one side of a high value resistor 6 whose other side is attached to the other metal contact 2.

In this condition the fuse wire 4 is intact, and current can pass from.one,-contact 2 to the other contact 3 travelling along the path of the fuse wire 4.

Figure 2. shows a fuse cartridge where the fuse wire 4 is broken and when current .i.s applied to the metal contact 2, electricity cannot pass through the broken fuse wire 4 and finds a path through the resistor and the bulb to the other contact 3. .In this condition, the bulb lights up and due to the high resistance created by the presence of the bulb and the resistor, the amount of current flowing to the circuit is very very minute and therefore safe.

Claims (2)

1. This self diagnostic illuminating electric fuse has an in-built micro lamp which lights up when the fuse wire burns out and with this illuminating features a blown out fuse is easily detected by the naked eye without the need for any testing equipment.

2. This self diagnostic illuminating electric fuse as claimed in 1 can be applied to any appliance or alachinery where ever electricity is used.