Lightning exposure, SPD selection, coordination, and backup protection
SPD Calculator
Choose a starting surge protective device type for AC, DC, or PV systems based on exposure, installation point, and system earthing.
Open calculatorSurge & Lightning Protection Tools
Tools for lightning-risk screening and AC, DC, and PV SPD type, voltage, coordination, and backup-fuse selection.
4 calculatorsLightning exposure, SPD selection, coordination, and backup protection
Advanced SPD Selection Calculator
Select a preliminary SPD type, connection arrangement, Uc or Ucpv range, discharge-duty level, and backup-protection checks.
Open calculatorLightning exposure, SPD selection, coordination, and backup protection
Lightning Risk Assessment Calculator
Estimate a simplified lightning exposure score from building collection area, location, thunderstorm activity, and incoming lines.
Open calculatorLightning exposure, SPD selection, coordination, and backup protection
SPD Backup Fuse Selection Calculator
Screen an SPD backup fuse or MCB rating from the SPD datasheet maximum backup protection and prospective fault current.
Open calculatorPlan exposure, SPD duty, and coordination
Surge protection selection begins with lightning exposure, supply route, installation point, earthing system, nominal voltage, equipment withstand, and coordination between protective stages.
SPD Type, Uc, Up, In, Imax, Iimp, short-circuit rating, backup protection, connection length, and wiring arrangement must be considered together.
Select and coordinate the protection stages
Type 1 addresses partial lightning current at exposed service origins, Type 2 limits switching and induced surges in distribution, and Type 3 provides local fine protection near sensitive equipment. Combined devices can cover more than one duty when correctly rated.
A low protective level on paper can be defeated by long connection leads. Installation geometry and bonding are part of SPD performance, not an afterthought.
Applications
Where these calculators fit
Building and panel protection
Screen SPD type from LPS, supply exposure, installation point, and downstream equipment.
PV and DC systems
Check maximum operating voltage, array configuration, polarity, and DC-specific SPD construction.
Coordination and backup
Review upstream/downstream SPD stages, distance, backup fuse, and prospective fault current.
FAQ
What is the difference between Type 1 and Type 2 SPD?
Type 1 is tested for partial lightning-current duty and is commonly used at exposed origins. Type 2 is tested for induced and switching surge duty in distribution systems.
Can a lower Up value always be considered better?
Only when Uc, system compatibility, energy duty, coordination, lead length, and equipment withstand are also satisfied.
When is SPD backup protection required?
Follow the exact SPD datasheet. The requirement and maximum backup rating depend on the SPD design, upstream device, and prospective short-circuit current.
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