Large Motor starting 103: Motor starting methods – how to choose the right one

January 8, 2019 admin bearing problems, inertia, load torque, locked rotor torque, mechanical stress, Mining/Metals/Minerals, motor starters, motor starting, Oil and Gas, soft-starter, starting methods, starting solutions, thermal capacity, variable speed drive, voltage drop

Credit to Author: Delcho Penkov| Date: Tue, 08 Jan 2019 12:36:11 +0000

This is the third post in our series on motor management covering various aspects of motor integration in an electrical network and the industrial process.

In the first, the electrical, thermal and mechanical constraints necessary to consider for large motor starting have been presented in detail. In the second post the typical application constraints have been introduced.

In this post we will try to answer the question: how to select the right motor starting solution for a concrete application?

There are several motor starting solutions that we can compare simply through the next table:

More detailed comparison of motor starting solutions can be found in this white paper: “Modeling of Motor Starting Methods in EMTP-ATP“.

By looking on the table we can decide that a variable speed drive is the solution for each case. And this would be right in the principle. However, the final decision will depend on several installation criteria which is related to:

Economical interest – the cost of the solution
Engineering simplicity – the efforts to evaluate this solution and to commission it
Maintenance easiness – which is also related to the cost of the maintenance
Footprint
Weight
Energy saving – the possibility to reduce energy consumption for some applications, for example when the operation is integrating idle cycles or reduced flow rate
Flexibility of adaptation – for varying operational conditions of flow, pressure, operating cycle

The next table provides a relative comparison of the above solutions for these installation criteria. It shows that the basic, contactor-based starting methods are also the most cost effective and easier for maintenance; but from the previous table we can see that these also cause the most stress on the network and the load:

You can find more information about large motor starting in the PCIC Conference tutorial here.

Learn more about motor management here.

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