Glossary

Meter

Overcurrent protective device (e.g. fuse or circuit breaker) located outside of the arrester on the infeed side to interrupt the power-frequency follow current as soon as the breaking capacity of the surge protective device is exceeded. No additional backup fuse is required since the backup fuse is already integrated in the SPD.

The  maximum  continuous  operating  voltage  (maximum permissible operating voltage) is the r.m.s. value of the maximum voltage which may be connected to the corresponding terminals of the surge protective device during operation. This is the maximum voltage on the arrester in the defined nonconducting state, which reverts the arrester back to this state after it has tripped and discharged. The value of UC depends on the nominal voltage of the system to be protected and the installer’s specifications (IEC 60364-5-534).

Value of the maximum d.c. voltage that may be permanently applied to the terminals of the SPD. To ensure that UCPV is higher than the maximum open-circuit voltage of the PV system in case of all external influences (e.g. ambient temperature, solar radiation intensity), UCPV must be higher than this maximum open-circuit voltage by a factor of 1.2 (according to  CLC/TS 50539-12). This factor of 1.2 ensures that the SPDs are not incorrectly dimensioned.

The maximum discharge current is the maximum peak value of the 8/20 μs impulse current which the device can safely discharge.

The maximum transmission capacity defines the maximum high-frequency power which can be transmitted via a coaxial surge protective device without interfering with the protection component.

Measuring and Control Equipment

Main Distribution Board

Main Earthing Busbar

Main Low-Voltage Distribution Board

Metal Oxide Varistor

Measuring Transducer

Medium Voltage