CYME power engineering software features a Dynamic Motor Starting Analysis optional module which is dedicated to simulating the effects of induction and synchronous motor starting in three-phase electric power systems. This module is a reliable and easy to use tool for assessing system voltage dips and acceleration times of motors, using a variety of starting methods.

The selection of the motor to be started along with the starting method is defined in a grid-style study dialog box. The study dialog box also gives the user the option to change the status of any motor in the network. This includes the switching of motors either to off, running, locked rotor or starting.

The Induction Motor Starting analysis takes into account the inertial effects of the motor, user-defined load curves and supports several starting methods as listed below:

• Direct on line
• Capacitor assisted
• Resistor or inductor
• Open and closed transition auto-transformer starting
• Soft starter with:
• Current ramp
• Voltage ramp
• Current limit
• Slip ring resistor insertion
• Manufacturer supplied curves
• Variable frequency drive
• Open and closed transition Star Delta starting

The above motor starting assistance methods are also supported in our transient stability program CYMSTAB.

The Synchronous Motor Starting analysis takes into account the inertial effects of the motor, user-defined load curves and Excitation system parameters to synchronize the motor when the speed is approaching synchronous speed. The algorithm takes into account the pulsating behavior of a starting Synchronous Motor due to the nature of the winding connections.

The program supports several starting methods, as follows:

• Across the line starting
• Shunt capacitor-assisted starting
• Resistor and/or inductor assisted starting
• Open/closed auto-transformer starting

A detailed user-defined load torque representation is provided with the program along with the opportunity to plot the nominal electrical and mechanical torque curves prior to starting the motor.

The load torque data can be entered from manufacturer data curves or with the general equation of load torque versus speed. In addition, default load curve characteristics of typical mechanical loads such as pumps, blowers, fans, feed drive and conveyer belts are also included.

In the absence of detailed information, the module includes support functions for deducing the equivalent circuit parameters for single circuit rotor, double circuit rotor or deep bar circuit rotor induction motors, utilizing either of the following information:

• Locked rotor and no load test
• Locked rotor and load test
• Nominal conditions
• Starting conditions
• Manufacturer curve data

This module also supports the estimation of synchronous motor electrical parameters from physical quantities.

The CYMVIEW program is common to all simulation modules and generates a variety of charts. CYMVIEW is capable of managing the time and frequency results of different CYME modules.

This includes charts and reports for motor bus voltage, starting current, power factor, electrical and mechanical torque versus time or speed. In addition, the time/current curve is generated for protective device coordination purposes.