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Yes, the distance between the arresters would be same as distance between the bushings. But the distance between the bushing and arrester doesn't need to be so much and I think the vendor is not applying the clearance rule properly?

Hi, The general clearances required for 230kV system are: 81” phase to phase and 70” phase to ground Do these clearances apply for surge arresters as well? For example, we have a transformer vendor who is using these reference distances to mount the arresters away from the bushings on the...

Marmite - I agree that the fault current will be more than 0.73Amps. I take back my statement, I gotta get back to my basics. Thanks for the correction!

Depends on how sensitive the 138kV differential is set to trip. The SSVT is only 100kVA @ 138kV = 0.73Amps. That's too small a current for differential to pick - up.

But in any case I am still trying to understand the consequences of installing underrated fuse? Sure, I will not recommend it :-)

Thanks Rafiq. I agree that engineering design and perhaps code also does not allow for underrated fuse. I thought the fuse will anyways blows off much less than 12.5kA...

Marmite - In this case the fuse is actually underrated for short circuit fault. Its never meant for overcurrent. Available short circuit at the bus - 20kA Fuse capability - 12.5kA

Alehman, Can you explain why? I may be missing some basics here :(

Hi, I need to hook up 138kV, 1ph ssvt (inductive type) to a bus via fuse link disconnect. The maximum SLG fault current at that bus can be 20kA (symmetrical) from my study. But, the maximum fuse rating available in the market is only 12.5kA (symmetrical). Can I still use this fuse to protect...