To prevent burning the motor, make sure to firstly identify if the 9 leads motor is factory pre-configured in the star (wye) or delta configuration before attempting any wiring connection and installing power to run the motor. now considering your case you have delta motor with name plate full load of 3A (say) this is the line current and the actual current in the winding will be 3/1.732 = 1.732A. Such motors in star formation would draw 1/3 the staring current, compared to the starting current at delta formation. In Delta connection, the three windings interconnection looks like a short circuit, but this is not true, if the system is balanced, then the value of the algebraic sum of all voltages around the mesh is zero in Delta connection.. Electric Motor Terminal Box Connections. Delta is connecting the motor windings up in 'parallel'. The star Contactor which used to short the motor terminal U2,V2 ,W2 so that it obtain the star Connection of the motor.Due to star Connection the one third of DOL current is provide to the motor ,thus reducing the high inrush current inherent with large capacity motors at startup. STAR DELTA connection Diagram and Working principle. When a terminal is open in Δ, then there is no chance of flowing currents with basic frequency around the closed mesh. Once the motor reaches it’s near about the operating speed, the winding connection would be changed back to normal Delta formation. note that the motor full load current is specified for the connection type mentioned on the name plate. The connection of a three-phase induction motor with a star delta … In the UK the nominal voltage is 400 volts 3 phase 50 Hz. when my motors turns from star to delta connection my ELCB which is 4 pole 63/30mA trip. Well i am installing one 37kW load Star-delta motor. Connecting polyphase motors in star is a ‘series’ connection of the windings. 3) Due to the starting current is reduced to approximately 1/3 of the nominal current, starting torque is also reduced to 1/3. 2) The supply voltage must be the same as the rated motor voltage for Delta connection. ELECTRIC MOTOR TERMINAL BOX CONNECTIONS. when i disconnect all the wires from the terminal block and run … Disadvantages of Star delta starter 1) Star delta starter can only useful to motors where the six motor terminals can be accessed. The input voltage to be considered, your input voltage, if it is 415v and motor operating voltage is also 415v, then you can connect either star or delta of the motor terminals. rest of all the isolator and MCB remain same. So you just link them up in series and that becomes your star and neutral point like at a transformer. A star delta is used for a cage motor designed to run normally on the delta connected stator winding. As a rule ,we set motor overloads as per Table 44 on the CECode or possibly any other code .This rule says that for motors with a Sfactor of 1.15 OLoad is set at 115% of motor nameplate FLAmps or Table 44 and 125% for motors with a 1.25 Sf.This is true for most motors unless ,they have a Star/Delta starter. ... Below is a diagram of the Star/Delta connections. Descriptions: A Dual starter connects the motor terminals directly to the power supply.Hence, the motor is subjected to the full voltage of the power supply.Consequently, high starting current flows through the motor. This type of starting is suitable for small motors below 5 hp (3.75 kW). EDIT: My initial answer was published without sufficient study of the applicable connection diagram—which should be a major step in ANY electrical work. Normally on electric motor nameplates we see either 220-240/380-415 volts on smaller motors or 380-415/660-720 volts on larger sizes. pl. motor.