Indoor current transformer cable KOLMA
Current transformers cable type KOLMA are suitable for the measurement of the sum of three-phase currents in a 3-phase cable.
KOLMA is usually used together with earth-fault protection relay.
A current transformer without primary conductor and primary insulation of its own, which can be mounted over an insulated cable or an insulated busbar.
Under normal operating conditions this sum is zero. In the event of an earth-fault the sum of the currents is equal to the earth-faul current and a corresponding current flows in the secondary.
These transformers are used together with static earth-fault relays. The cable current transformers can generally be used when measuring the residual current e.g. to prewarn of, or locate an earth-fault. An uninsulated busbar or low voltage cable serves as the primary conductor.
Highest voltage for equipment............ 0.72 kV
Primary current................................... 1 250 A
- Ready to be used together with earth-fault protection relay
- 12 ratios per one CT can be used
- Easy mounting by base plate
- Test winding as part of the transformer available
- For rated primary currents of up to 1250 A (higher values on demand)
- For measuring of the sum of the three phase current
- With up to 5 secondary terminals