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S7-200 Tip : Wound Rotor

Special Hardware Requirements: None

This program example provides an automatic, four-resistor startup of a three-phase, wound rotor induction motor. The motor starts with full rotor resistance. After a specified time has run out, the first rotor contactor closes, removing part of the rotor resistance. As additional time intervals pass, the rest of the rotor contactors close one by one, decreasing the rotor resistance each time until the resistance is bypassed completely and the motor runs at the rated rotational speed.

S7-200 Tip : Stator-Resistance Starting

Special Hardware Requirements: None

In this example program, a squirrel-cage rotor with short-circuit soft start switching makes the automatic startup of a three-phase induction motor possible. With this short-circuit soft start, the motor starts up with a decreased rotational speed and attains the rated rotational speed only after a certain amount of time.

S7-200 Tips : Star Delta Starter 2

Special Hardware Requirements: None

This program example controls star-delta starting for a three-phase induction motor. Application Tip No. 12 is supplemented with the acknowledgement of the actual circuit states of the motor starters. If the star starter is defective, for example, the starter acknowledgement recognizes this fault. After the 5-s delay time, SIMATIC S7-200 does not switch to the delta stage and therefore avoids any possible damage.

S7-200 Tips : Star Delta Starter 1

Special Hardware Requirements: None

This programming example controls star-delta startup for a three-phase induction motor.
Use the ON momentary contact switch at input I0.0 to start the motor in the high star level. The motor changes to the delta level after the set time of 5 s has run out.

S7-200 Tip : Changing Direction Speed

Special Hardware Requirements: None

This program example, an expansion of Application Tip No. 10, controls a three-phase induction motor with two separate windings for various rotational speeds and two possible rotational directions. The momentary contact switches at the inputs switch on the motor.

It is possible to change between a higher and lower rotational speed per rotational direction at any time. The motor requires about 5 s to brake and to start up again in the opposite direction.
The flashing light at output Q0.5 displays the waiting period.