How are harmonic currents created?

Harmonic currents and voltages are created by non-linear loads connected on the power distribution system.  All power electronic converters used in different types of electronic systems can increase harmonic disturbances by injecting harmonic currents directly into the supply network.  Common non-linear loads include motor starters, variable speed drives, computers and other devices such as electronic […]

What is the effect of harmonics?

Harmonics can cause cables to overheat, damaging their insulation.  Motors may also overheat or become noisy and torque oscillations in the rotor can lead to mechanical resonance and vibration.  Capacitors overheat with, in the most severe cases, the risk of explosion as the dielectric breaks down.  Then you really will need our superhero Captain Q […]

What are harmonics?

Harmonic distortion is a form of electrical pollution that can cause problems if the sum of the harmonic currents increases above certain limits. A harmonic current is one with a frequency at a multiple of the fundamental frequency, for instance a 250 Hz current on a 50Hz network is the 5th harmonic.  The 250 Hz […]

I have a 90kW motor with soft starter 90kW installed. How much kVA Generator do I require for the motor?

Limited information means you need to make a few assumptions on power factor and efficiency. Assume PF of 0.75 and efficiency of 90% kVA = (kW / Power factor) / efficiency so kVA = (90 / 0.75) / 0.9 = 133.33 kVA So 133.33 kVA minimum but better to add a little extra to be […]

Why use a bypass contractor with a soft starter?

The Bypass contactor opens when the motor reaches full speed to reduce power (heat) losses in the solid-state power section. This translates to much smaller enclosures without need for special cooling. Also, the bypass contactor is internal to the soft starter, eliminating the need for additional devices, further reducing enclosure sizes and minimizing installation time. […]

What is the difference between a VSD and a Soft Start Starter?

We are frequently asked, what the difference is between a variable speed drive and a soft starter? The difference is the speed that the motor can run when at full speed. With a soft start starter, the motor is reduced when voltage is started; and then when the motor is at full speed, or a […]

I have a 90kW motor with soft starter 90kW installed. How much kVA Generator do I require for the motor?

Limited information means you need to make a few assumptions on power factor and efficiency. Assume PF of 0.75 and efficiency of 90 % kVA = (kW / Power factor) / efficiency so kVA = (90 / 0.75) / 0.9 = 133.33 kVA So 133.33 kVA minimum but better to add a little extra to […]

When should I consider buying an energy-efficient motor?

Energy-efficient motors should be considered in the following circumstances: For all new installations When purchasing equipment packages, such as compressors, HVAC systems, and pumps When major modifications are made to facilities or processes Instead of rewinding older, standard efficiency units To replace oversized and under-loaded motors As part of a preventive maintenance or energy conservation […]