Hi All,
First post so please take it easy on a guy. I'm trying to size a CT for the replacement of a Ground Fault System on a clients transformer. It is a 25kV - 208/120V Dyn1 1000KVA dry type. Solidly grounded. The phase CT's are 3000:5 and I was looking to add a Neutral CT of the same ratio. I'm upgrading the SEL787 card to include a neutral input.... (Someone else sold them a 787...) My co-worker commented that the ratio is too high and I should install something with a lower ratio. I believe you would use a lower ratio if you were installing a ZSCT or if it was a high impedance grounded system. Please correct me if I'm wrong.
First post so please take it easy on a guy. I'm trying to size a CT for the replacement of a Ground Fault System on a clients transformer. It is a 25kV - 208/120V Dyn1 1000KVA dry type. Solidly grounded. The phase CT's are 3000:5 and I was looking to add a Neutral CT of the same ratio. I'm upgrading the SEL787 card to include a neutral input.... (Someone else sold them a 787...) My co-worker commented that the ratio is too high and I should install something with a lower ratio. I believe you would use a lower ratio if you were installing a ZSCT or if it was a high impedance grounded system. Please correct me if I'm wrong.
