38
5-2-3 Connection of Thermal Overload Relay with CT
When CT side is V-connected, 2 set of CT can make 3-phase protection. Then, in order to ensure correct operation,
make wiring as shown in Fig. 33 and Fig. 34 by paying attention to the mounting direction and polarity.
Fig. 33 Connection diagram Fig. 34 Mounting of CT and wiring
A current flows to the 3 heaters of the thermal overload relay at 3-phase overload.
Fig. 35
Even if phase failure occurs, current flows to the 2 heaters without phase failure, regardless of the insertion phase of
CT; the same operation is made as the 3-phase thermal overload relay not using CT.
Fig. 36
Where 3sets of CT are used, individual CT's are connected to the respective heaters of the thermal overload relay as
shown in Fig. 37 and Fig. 38.
Then, even if the CT polarities are arranged uniformly, protection can be ensured.
To Next Page
Loading...
