Willo Instruction Manual
8
Appendices
Surge Protection Device
The distribution panel of Willo contains a Surge Protection Device (SPD) based upon Metal
Oxide Varistor (MOV) technology connected between live, neutral and the earth conductors to
protect the internal electronics from over voltage surges caused in particular by nearby lightning
strikes.
Under normal voltage, MOV is in a high-impedance state (open circuit
) and won’t impact the
normal operating of the line. The fault window indicates green.
When a transient pulse over-voltage occurs due to lightning or other causes, the module
conducts within nanoseconds, clamps the voltage and diverts the surge current to earth. When
the over-voltage disappears, the module automatically resumes the high-impedance state.
Should the module be subject to sustained over voltage, over temperature protection devices
within the module will activate to prevent the MOV from catching fire. Overcurrent protection
also exists and should any of these protection devices activate, the fault window will indicate
RED. In this event the Surge Protection Device is no longer functional and requires
replacement.
SPD Specifications:
Part Number
DXH06-FCS/1 + 1R40
Maximum Continuous Voltage
385VAC
Nominal Discharge Current
20KA (8/20μs)
Maximum Discharge Current
40KA (8/20μs)
Voltage Limitation
1.8KV
Protected Modes
L - N, N - PE
Warning
Status Window, Remote Switch Connection
Response Time
25ns
