Surge Capacity and Surge Capability

[Ranch]

Looking for some help comparing TVSS units, one rated "160KA surge capacity" the other rated "Surge capability 100kA/mode maximum"

I'm not sure if these ratings are apples to apples and the "/mode" is new to me. Can someone help me interpret this?

Thanks in advance

 

[Ranch]

I'm going to reply to myself, apples to apples one is 160kA, the other 200kA

So I'm good, apologies for cluttering ....

 

[dereckbc]

Manufactures like to use marketing tricks. The one you are looking for is amps per mode, it is the only one that counts. What the manufactures do is post the total of all modes. For example they may say 240 KA for their 3-P wye device. But if you look deeper it is a 3 mode device (L1-N, L2-N, and L3-N) with 80KA per mode, 160 KA per phase, and 240KA capacity

Here is a link of specs for a line I helped develop some years ago. You will see exactly what I mean. These devices are 65KA per mode, and 130KA per phase.

 

[Ranch]

dereckbc,

Agreed on the marketing tricks comment, thank you, we sure need to be careful with suppliers.

Other notes - 12 pulse system fed from two transformer secondary windings, Delta & WYE with high resistance grounding (zig zag derived neutral on the Delta). TVSS connected only to phase conductors and ground (no neutral connections) on each secondary.

I'm trying to make something read correctly - With respect to each transformer secondary, per mode is the only relevant rating. But consider also there are six phase conductors feeding the system ? so how might I state something describing using a pair of TVSS I have six modes (??)

 

[dereckbc]

Ranch I am not sure exactly what it is you are trying to do, but maybe this will help.

If it is a service or a SDS you only need to install the SPD's across the phases or coils of the transformer whether it be delta or wye connected. L-G, and N-G modes serve no purpose because in a wye system N-G is solidly bonded, and in delta G has no function.

Once you move down stream away from a service or SDS like a branch panel or feeder, the L-G and N-G modes become important and should be provided for.

Hope that makes since.

 

[DanZ]

I'm glad I'm not the only one to have problems with Manufacturer's specs! Most of the dental equipment specs I get are 120V 20A or 240V 30A. I know they're specing nominal voltage and CB size, but no one in the chain of communication knows the difference between CB and FLA! On top of that, they've stopped using cut sheets!