ICS Engineering Inc.
Electrical Consulting | Communications | Automation

Motor Starting Studies

Electrical Load Calculations for equipment in Alberta and BC
Industrial motors in Vancouver, BC.

Motor starting studies are performed on industrial and large commercial systems where large motors can have unwanted consequences on the performance of it and surrounding equipment.

The starting current of most AC motors is several times the normal full rated load current when starting from full line voltage. These large current requirements can result in:

  • Nuisance tripping of protection breakers.
  • Excessive running currents.
  • Drop in terminal voltage.
  • Triggering of under voltage relays.
  • Low starting torques resulting in a failure to start.
  • Stalling of other running motors connected to the power system.
  • Equipment damage of heaters, power supplies and other electrical gear.
  • Computer and control systems rebooting as their low voltage detectors trigger.

Dimming of lights as motors start up is a clear indicator that the power system may need investigation. It may have insufficient capacity or a better motor starting strategy may be required.

The technical stuff - The output torque is related to square of the voltage. If an AC induction or synchronous motor is started while attached to a mechanical load on the shaft, inrush current can be up to 6 times full-load current and will be drawn for a longer time.

The power system should be able to supply enough inrush current to any motor while providing normal service to the rest of the industrial or commercial system. MCA vs FLA parameters are use to properly size the branch conductors.

As electrical consultants, motor starting studies help to improve the reliability engineering for the entire building system and industrial complex. We help to determine the best way to start large motors in a group help keep your these large investments running and lasting longer.

Motor Starting Strategies

There are various ways to start a motor including:

  • Direct supply voltage
  • Direct supply voltage with compensation
  • Auto-transformers
  • Soft starters
  • Star-Delta Starters
  • Variable Frequency Drives (VFD)

Motor Starting Analysis

Motor starting analysis is one component of power system studies and starts at the client site to gather current and historical information. Then simulations are run using these measured data and information from the manufacturer.

From our computer models, we will be able to predict the operation for new installations and to diagnosis problems and offer solutions for existing motor installations.

We use both static and dynamic models to simulate the starting sequence of motors and usually rely on dynamic analysis to reproduce observed and measured starting conditions.

Motor Service Factor

ICS Engineering Inc.
Edmonton 587-557-1152