ETAP TUTORIALS: MOTOR STARTING ANALYSIS

Tuesday, May 17, 2011

This ETAP Tutorial introduces the Motor Starting Analysis or Motor Acceleration module. It will show the dynamic and static models that can be used to simulate real motor characteristics. The minimum amount of data essential to run each type of study will also be inputted.

ETAP Motor Starting Analysis assists electrical engineers to simulate and compute motor acceleration time and the voltage impact of motor starting on electrical systems. The motor starting (acceleartion) module is fully capable of starting individual motors or transitioning the whole electrical power system to another condition. 
Motor Starting Analysis
Motor Starting Analysis
Background

The motor appears to the system as a small impedance connected to the bus during motor starting period. Subsequently, it draws an inrush current about six times of its rated current, which could result to voltage sags or dips, affecting the operation of other loads. Basically, the objectives in performing a motor starting analysis are:

Ø  Examine whether the motor can be effectively started under the operating conditions
Ø  Check if starting the motor will hinder normal operation of other system connected loads

As mentioned, the ETAP Motor Acceleration module presents two types of calculations: Static Motor Starting and Dynamic Motor Acceleration.

Static Motor Starting

The motors are represented by the locked-rotor impedance during acceleration time, simulating the worst effect on normal operating loads. This is appropriate for checking the impact of motor starting on the system when the dynamic model is unavailable.

Dynamic Motor Acceleration

In this setup, the motors are dynamically modelled. This method is used to verify if a motor can be started and how much time is needed for the motor to achieve its rated speed, as well as to find out the effects of voltage sags on the system being considered.

Motor Starting Analysis

Link 1: PDF Tutorial

ETAP Tutorial Outline:
Ø  Running a Static Motor Starting Study
Ø  Running a Dynamic Motor Starting Study

Link 2: Play Motor Starting (Static) Video Tutorial




Link 3: Play Motor Starting (Dynamic) Video Tutorial



Reference:
ETAP Help File

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I am an Electrical Engineer with a Masters Degree in Business Administration. My interest is in Power Quality and Protective Relaying. I have been working in an electric distribution utility for about seven years now as a Planning & Design Engineer. I handle PQ studies, power system analysis and capital budgeting for company projects.