Neozed fuses

The NEOZED design introduced in 1967 is the more compact successor to the DIAZED fuse. NEOZED fuses are only used in the electrical installation in the residential area as a protection of the power supply of permanently connected devices, for example of flow-through heaters, and were otherwise usually replaced by circuit breakers. In industry, on the other hand, they are often used as overvoltage protection for power tools and machines. NEOZED fuses also perform their service reliably in combination with a motor circuit breaker. A NEOZED fuse is a fuse. The complete fuse device consists of the fuse base and a contact protection above it. The melt or fuse insert, together with the matching adapter sleeve, is inserted in the base. Finally, the fuse insert is secured with the screw cap.

Illustration of NEOZED circuit
U = voltage source
F = fuse
H1 & H2 = load

A NEOZED fuse consists of a fusible element designed for a specific nominal current, which is made of electrolytic copper or fine silver. The fuse element is usually surrounded by quartz sand or air. This coating ensures that the resulting arc is cooled when the fuse is triggered. In addition, the contacts (head and foot contact) are located on both sides of the fuse. All these components are held together by the body of the fuse. This consists of insulating material such as ceramic, plastic or composite material and ensures that the arc created inside cannot cause any damage.

And what was happening if the NEOZED fuse link was triggered due to an overvoltage? In this case, the fuse literally blows. The melt conductor is melted by the flowing current. More precisely, the melt conductor changes the aggregate state from solid to liquid to gaseous. In the gaseous state, an arc is finally formed, which interrupts the current flow at the same time. The tripping behavior of device fuses is divided into FF (super-fast), F (fast-blow), M (medium-blow), T (slow-blow) and TT (super-blow). This refers to the response time that a fuse needs to trigger. While an FF fuse already responds to short voltage peaks, fuses with increasing inertia have a greater tolerance in their tripping behavior.

NEOZED fuses are divided into different operating classes. Here are some of the most common classes: The standard type for general applications is called GG. The tripping behavior of this type is slow-blow, i.e. slow at low short-circuit currents and fast-blow at high currents. The type GR is intended for the protection of semiconductor components (super-quick-acting). The type GS (super-quick-acting) fuses are also used for semiconductor elements and for line protection. The GF type (quick-acting) is used for industrial plants, power plants or similar. For photovoltaic systems, however, the type gPV is used (super-fast).

In contrast to a miniature circuit breaker, a fuse must be replaced after it has tripped. Bridging, however, is not permitted and can be fatal. It should therefore be left out! Make sure that the new fuse also has the appropriate rated current and the appropriate characteristic curve. If this is not observed, sufficient protection of the connected devices is no longer guaranteed in the event of an overvoltage. Please also note that a fuse is always subject to an aging process. During its life cycle, the tripping behavior of the fuse changes due to current peaks caused when a device is switched on, as well as diffusion processes. An original sluggish fuse tends to become more agile over time.