What is a Voltage Sag Compensator? Working Principle and Applications

Learn how a voltage sag compensator shields automated plants from grid disturbances, and how CTR’s Instantaneous Voltage Dip Compensator saves over 80% energy compared with online UPS systems.

Voltage Dip Graphic

Introduction

A grid disturbance lasting less than a second can halt an entire factory floor. Drives trip, controllers reset, and a production run that took hours to stabilise has to begin again, often with material wasted along the way. A voltage sag compensator is built to prevent that chain of events. It bridges the gap while the grid recovers, so machinery never notices anything went wrong.

Understanding Voltage Sags

A sag is a short-lived fall in supply voltage, lasting anywhere from a fraction of a cycle to a few seconds. A micro-interruption is an even briefer loss of supply. Typical triggers include:

Lightning strikes and faults on the utility network

Switching operations by the power utility

Large motors starting on the same feeder

This is the heShort circuits elsewhere inside the plantading

Most of these events end before anyone on the shop floor notices. Modern automation, however, is far less forgiving than the people supervising it.

What Does a Voltage Sag Compensator Do?

It keeps sensitive equipment powered while the incoming supply is unstable. CTR’s Instantaneous Voltage Dip Compensator is designed to prevent costly stoppages by taking over the power demand through integrated energy storage, which keeps the electrical system stable during the event.

It is recommended for industries where dips and micro-interruptions are a recurring headache.

Voltage Sag Compensator

Working Principle

Detection

The unit continuously watches the incoming supply and recognises a disturbance the moment it begins.

Instant Reactive Response

Ultra-fast reactive current is delivered to counter the sag. This quick reaction is a defining strength of the unit, which functions both as a power conditioner and as a sag corrector.

Energy-storage Support

For the length of the event, the integrated storage supplies real power to the equipment. CTR’s unit offers active power support for 1 second as standard, extendable to 5 seconds or more on request. That window covers the majority of grid disturbances.

Return To The Grid

When the supply stabilises, the unit hands the demand back to the grid, and equipment keeps running without a hiccup.

Key Features

Supply Options

 AC 400 V and 690 V

Standard Ratings

345 kW, 660 kW, 1000 kW and 1500 kW

Ride-through Time

1 second, customisable up to 5 seconds or more

Efficiency

Over 80% energy savings versus online UPS systems

Dual Role

Power conditioning along with sag correction

Standards

Conforms to IS 13340:1993 and meets the required technical specifications

Where It Is Used

Automotive plants and assembly lines

Steel, cement, paper and chemical works

Textile, plastics and packaging units

Electronics and precision manufacturing

Sag Compensator vs. Online UPS

Sag Compensator Online UPS
Built for Sags and micro-interruptions Extended outages
Support time 1 second (up to 5 seconds or more) Minutes to hours
Energy consumption Over 80% lower (per CTR) Constant conversion losses
Best suited to Plant-scale demand, 345 to 1500 kW Small equipment needing long backup

When the trouble is brief grid events rather than prolonged blackouts, a sag compensator delivers protection at a fraction of the running cost.

Selecting the Right Unit

  1. Study your disturbances: Note how often they strike and how long they last
  2. Match the supply: 400 V or 690 V
  3. Size it properly: Pick from 345, 660, 1000 or 1500 kW
  4. Choose the hold-up time: Standard 1 second, or longer if your site needs it
  5. Consult specialists: CTR’s engineers can recommend the ideal configuration

Conclusion

Short grid disturbances carry a long list of consequences: idle machines, wasted material, and lost orders. A voltage sag compensator removes that risk by stepping in instantly and drawing on stored energy until the grid steadies. CTR’s Instantaneous Voltage Dip Compensator offers ratings from 345 kW to 1500 kW, a customisable support window, and energy savings above 80% compared with online UPS systems.