2EL4

Gas Discharge Tube (GDT) Replacement Planar Passivated Junctions in a Protected Cell Construction
Low Off-State Current Extended Service Life
Soldered Copper Electrodes High Current Capability Cell Construction Short Circuits Under Excessive Current Conditions

2EL4 are primary protector components for semiconductor arrester assemblies intended to meet the generic requirements of Bellcore GR-974-CORE (November 1994) or ITU-T Recommendation K28 (03/93). To conform to the specified environmental requirements, the 2ELx must be installed in a housing which maintains a stable microclimate during these tests (e.g. FIGURE I.1/K28).

The protector consists of a symmetrical voltage-triggered bidirectional thyristor. Overvoltages are initially clipped by breakdown clamping until the voltage rises to the breakover level, which causes the device to crowbar into a low-voltage on state. This low-voltage on state causes the current resulting from the overvoltage to be safely diverted through the device. The high crowbar holding current prevents d.c. latchup as the diverted current subsides. This 2EL4 range consists of three voltage variants to meet various maximum system voltage levels. They are guaranteed to voltage limit and withstand the listed international lightning surges in both polarities.

2EL4 are constructed using two nickel plated copper electrodes soldered to each side of the silicon chip. This packaging approach allows heat to be removed from both sides of the silicon, resulting in the doubling of the devices thermal capacity, enabling a power line cross current capability of 10 A rms for 1 second. One of the 2ELx's copper electrodes is specially shaped to promote a progressive shorting action (at 50/60 Hz currents greater than 60 A). The assembly must hold the 2ELx in compression, so that the cell electrodes can be forced together during overstress testing. Under excessive power line cross conditions the 2EL4 will fail short circuit, providing maximum protection to the equipment.