IGEL's soft starter with a power level completely
IGEL’s soft starter with a power level completely galvanically isolated from the control level.
Credit: IGEL Electric
Soft starters replace your old mechanical solutions such as star-delta or autotransformers and are gaining market share in the electrical drive field previously dominated by variable frequency drives, writes Andreas Fornwald

Today’s soft starters have very little in common with the oversized units from the 1980s.

A modern medium voltage soft starter fits into a conventional control panel. This means capacities of up to 4 MW fit into the smallest of spaces or even directly on the application, depending on the requirements.

The capacity range is between 200 W and 30 MW and the voltage range is from 220 V up to 15,000 V.

With this power range, the soft starter technology covers 99 per cent of the drive assemblies needed on the market. But the development of modern drive assemblies is subject to far more stringent demands than the mere capacity range.

A holistic view of the installed components and their effects on each other as well as on other system components needs to be taken, particularly in relation to industry norms and standards.

The fact that the soft starter has no negative impact on other plant components and thus requires no additional filters and shielded cables facilitates development immensely. Moreover, its small footprint and minimal heat loss assist in the switch cabinet design.

The latest units have a number of features that provide additional benefits in certain applications. By far the most common feature is the integrated current limiter, which allows starting the motor with a defined maximum current.

This limited power requirement allows a more precise definition of the network load, whereby upstream components such as transformers or generators can be calculated more accurately.

Equally widespread is the start function for pump applications which is due to the fact that it eliminates crucial problems in pumping solutions.

Due to the complexity of the respective pipe systems, effective solutions cannot be achieved by predetermined ramps but only by an intelligent control system.

As a result, the service life of swing check valves is extended and, on the other hand, additional components such as automatic valves are saved on.

Many users are under a dangerous illusion in believing that every soft starter can reduce the load of a diesel generator.

This usually works only up to a certain load of the generator. This quickly leads to unstable processes in the generator, which become noticeable through fluctuating voltages and frequencies and can cause the drive assembly to fail. Top soft starters have automatic frequency adjustment that responds to the changed situation of the generator.

In March, IGEL Electric will unveil the ISA SL, the first soft starter with a power level that is completely galvanically isolated from the control level.

In combination with inductive transmission technology, IGEL increases the immunity and allows the cost-effective use of the soft starter. Because of such technological advancements, modern soft starters have long since fought for and won their place in electrical drive technology.

Andreas Fornwald is Chief Executive of IGEL Electric GmbH. For more information, please visit: www.igelelectric.de

Technical specification ISA-SL

  • Inductive technology for the transfer of ignition signals
  • Fully selectable version with two- or three-phase power section
  • Switching between two- and three-phase technology during the ongoing operation of the system
  • Supply Voltage model: Line to line 208-600 V (to be specified) + 10-15 per cent for all
  • Frequency: 45 – 65 Hz (fixed or variable frequency source)
  • Control supply: 115 V or 230 V (to be specified) +10-15 per cent
  • Load: Three phases, three wires, squirrel cage induction motor
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