Appendix B: UBZ-302M Operation with Motor in Star/Delta Switching Mode

Connect the UBZ-302M to motor operation in the star/delta switching mode according to the simplified scheme shown on Figure B.1 below.

When working in the star/delta switching mode the motor could be controlled in several ways:

• Turn OFF/ON of the motor by external circuit breaker (contactor) with simultaneous power supply OFF/ON to the input terminals of the UBZ-302M;
• Operation with the motor from the front panel of the UBZ-302M;
• Operation with the motor using interface USB/RS-485.

Symbol	Description	Symbol	Description
А	UBZ-302M	QF1, QF2	Circuit breaker
F1-F3	Fuses	R1, R2	Thermistor
K	Electromagnetic starter	T1-T3	Current transformers
М	Induction motor	T4	Differential transformer

Figure B.1 – Wiring diagram for the UBZ-302M for star/delta mode of operation

ATTENTION!!!

It is strictly prohibited to turn OFF the motor by external circuit breaker (contactor) without taking OFF the power supply from the input terminals of the UBZ-302M. As a very exception it’s possible to disconnect first the motor by external breaker (contactor) and then additionally turn the motor OFF from the front panel of the UBZ-302M or alternatively by giving the corresponding remote control command by interface USB/RS-485 to avoid the direct start on Delta.