HRC fuse Construction Working Advantages and Disadvantages

High Rupturing Capacity (H.R.C.) Fuses :
Q. Explain the constructional detail of high rupturing capacity cartridge fuse with neat sketch.
Q. Explain the constructional detail of H.R.C. fuse.
Q. Explain with neat sketch the working of HRC fuse.
Q. Explain the construction and working of HRC fuse with diagram.

HRC fuse Construction & Working :

• Figure (A) shows the essential parts of a typical HRC.
• HRC fuses mainly consist of a heat resisting ceramic body. Both the ends of ceramic body consist of metal end caps.
• A silver current carrying element is welded to these metal end caps.
• The current carrying element is completely surrounded by the filling powder.
• The filling material may be plaster of parries, chalk, quartz or marble dust.
• Filling material acts as an arc quenching and cooling medium when fuse element blows off due to excessive heat generated under abnormal condition.

• Under normal conditions, the fuse element is at a temperature below its melting point. Therefore, it carries the normal current without overheating.
• When a fault occurs, the current increases and the heat produced is sufficient to melt fuse element. Fuse element melt before the fault current reaches its first peak value.
• Vaporisation of metal silver element chemically reacts with filling powder and results in the formation of resistance substance and helps in quenching the arc.

Advantages of HRC fuses :

1. Speed of operation is very high.
2. Maintenance cost is practically zero.
3. They are capable of clearing high as well as low fault currents.
4. They do not deteriorate with age.
5. They provide reliable operation.
6. They are cheaper than other circuit interrupting devices of equal breaking capacity.

Disadvantages of HRC fuses :

1. Heat produced by the arc may affect the associated switches.
2. They have to be replaced after each operation.

Characteristics of HRC Fuse Element :
Q. Explain the important characteristics of high Rupturing Capacity (H.R.C) Fuse.

They should have following desirable characteristics.

1. Low melting point.
2. High conductivity.
3. Free from deterioration due to oxidation.
4. Low cost.