Current sensors - SCB

Q.

Current sensors - SCB

Ref.: § 5.24.2.2. measurements from SCB, and Table 18:

1) Is it really necessary to have the single measures of the current in each SCB branch, also considering the limited conduction time of the SCB?
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2) About current sensors for SCB, we see two possible alternative implementations; let us call "N" the number of parallel branches of the SCB:
a) A single high current DCCT rated 45 kA to measure the total current, with the addition of N sensors - one on each SCB branch - that give a signal when current variation is detected in the branch (in order to timely detect and manage if one branch fails)
b) N sensors (DCCTs), one per branch, with full scale rating around 45 kA / N x 1.2 (instead of 45 kA); the SCB total current will be the sum of the N DCCT outputs.

Are both solutions a) and b) acceptable?

A. 

1) Yes, because these data are useful for diagnostic and control purposes.
2) Both solutions can be acceptable. Nevertheless you consider that the level of redundancy is an evaluation feature of the technical offer, therefore a higher redundancy level will be evaluated with a higher score.

 

 

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