Matt circuit

S0 = ‘OFF’ Push button S1 = ‘ON’ Push button K1 = Line contactor K2 = Star contactor K3 = Delta contactor K4 = Star delta timer (7PU60 20) F2 = Overload relay F1 = Backup fuse F3 = Control circuit fuse This is a starting method that reduces the starting current and starting torque. The device normally consists of three contactors, an overload relay and a timer for setting the time in the star-position (starting position). The motor must be delta connected during a normal run, in order to be able to use this starting method. The received starting current is about 30 % of the starting current during direct on line start and the starting torque is reduced to about 25 % of the torque available at a D.O.L start. This starting method only works when the application is light loaded during the start. If the motor is too heavily loaded, there will not be enough torque to accelerate the motor up to speed before switching over to the delta position. When starting up pumps and fans for example, th...

Some motors starters at high current more than several times its current at full load condition. The effect of this to other is necessary tripping of circuit breakers. One way of reducing the high starting current of a motor is the start the motor with the low voltage at its winding. After a few seconds, when the motor is already running at its stable condition, the rated full voltage is applied to its winding. This system is called reduced voltage starting. One method of reducing the starting current of a motor is to connect the winding of the motor into WYE connection during the starting process and when the motor is running, the winding are connected into Delta, see figures 9(c) and (D). Note that at WYE connection the voltage across the motor windings is 220 volts, Figure below (D). CONTROL OPERATION Figure below (A) and (B) shows the power and control circuit of a “WYE-DELTA Reduced Voltage Starter”. A time delay relay (Timer) is in the control circuit. The timer TR will delay the...

Delta Airlines announced Thursday that it has adopted Microsoft's Windows Phone 8 platform and the Nokia Lumia 820 as its go-to handheld device for 19,000 flight attendants. The smartphones will be used to handle a range of tasks both on the ground and in the air.  The phones are running customized software for Delta from Avanade that runs on the Microsoft Dynamics for Retail mobile point-of sale platform. Delta believes that the system, together with Wi-Fi/4G connectivity provided by AT&T, will empower its flight attendants while also improving its customers' experiences throughout the boarding, flying and deplaning processes. The Lumia 820 is fairly compact, which makes it easy to carry around and use. It has a 4.3-inch ClearBlack display, a dual-core 1.5-GHz Snapdragon S4 processor, 1 GB of RAM, an 8-megapixel camera with Carl Zeiss optics, NFC and Nokia's suite of software.  Together with the Avanade software, the Lumia 820 should be a powerful ally for flight atten...