What is drop out fuse?

Drop out fuses and load drop out fuses are out door high-voltage protective devices.They are installed on the high-voltage side ofdistribution transformers or branch lines of distribution lines, used for short-circuit and overload protection as well as load current switching for transformers and lines.

The drop-out fuse consists of an insulating base, a fixed contact, a moving contact, and a fuse tube. The fixed contact is installed at both ends of the insulating support,and the moving contact is installed at both ends of the fuse tube. The fuse tube is composed of an inner arcextinguishing tube and an outer layer of phenolic paper tube or epoxy glass cloth tube.The load-drop-out fuse incorporates a spring-loaded auxiliary contact and an arc-extinguishing hood to enable the switching of load currents.

Working principle of drop out fuse

The drop-out fuse operates normally with the fuse tube closing position formed by the tension of the fuse wire.When a fault occurs in the system, the fault current rapidly melts thefuse wire, forming an electric arc. The arc-extinguishing tube is heated by the arc, releasing a large amount of gas, which creates high pressure inside the tube and forms a longitudinal blowout along the tube. The electric arc is rapidly elongated and extinguished.After the fuse wire melts, the lower moving contact loses tension and flips down, releasing the fuse tube from the lock, causing the fuse tube to drop and form a clear open position.

When disconnecting the load, the insulated rod is used to pull the moving contact. At this point, the moving and static contacts are still in contact. Continuing to pull the moving contact with the insulated rod, the auxiliary contact rapidly separates, generating an electric arc between the auxiliary contacts. The electric arc is elongated in the arc extinguishing cover slot, while the arc extinguishing cover generates gas. When the current reaches zero, the electric arc is extinguished.

Technique data

NDRW12 Series Drop-out Fuse 10-15KV

Rated Voltage  :10-15KV

Rated Current  :100A,200A

Breaking Current :8/10 kA

Power-frequency Withstand Voitag (kV): 40kV

Dimensions (cm) : 42×37×13.5

NDRW12 Series Drop-out Fuse 15-24KV

Rated Voltage  :15-24KV

Rated Current  :100A,200A

Breaking Current :10/12 kA

Power-frequency Withstand Voitag (kV): 45kV

Dimensions (cm) : 52×37×13.5

NDRW12 Series Drop-out Fuse 24-27KV

Rated Voltage  :24-27KV

Rated Current  :100A,200A

Breaking Current :10/12 kA

Power-frequency Withstand Voitag (kV): 45kV

Dimensions (cm) : 52×38×17

NDRW12 Series Drop-out Fuse 33-36KV

Rated Voltage  :33-36KV

Rated Current  :100A,200A

Breaking Current :10/12 kA

Power-frequency Withstand Voitag (kV): 45kV

Dimensions (cm) : 62×38×17