Hello,
I have questions about installation of surge protective device (SPD) modules on a single phase 230V TNC mains line (EU).
The engineer, who build the lightning protection system of my house, recommended to use Type 1 + Type 2 combined MOV protection device with Iimp=15kA (T1) and Imax=70kA (T2) and 50A back-up fuse (the main fuse to the house is 63A).
I found SPD devices at good price with Iimp=7kA (T1) and Imax=70kA (T2) and recommended <=50A back-up fuse. Everything is clearly described in the SPD datasheet, but my specific question #1 is can I use 2 identical 7kA SPD modules in parallel via a common 50A back-up fuse? Will they work as a single device with Iimp=14kA for 10/350 us impulses?
My question #2: If I buy SPD with recommended back-up gG fuse of <=160А (withstanding 10kA short circuit current), can I use this SPD via 50A back-up fuse? Will I limit the surge charasteristics of the device using a lower value fuse - and if so, what would be the limitation?
Thank you in advance!