Power quality phenomenon and telecommunication systems are not a good mix

24 April 2018

Telecommunication systems have been developing rapidly in recent years. What was once simply voice communications devices has now slowly morphed into data transmission as well. This new form of communication means that telecommunication systems are getting more advanced, making them more vulnerable to power quality problems because the electronics used for data transmission are more susceptible to sags / dips, swells, transients and harmonics.

Equipment tripping offline is costly

Telecommunication equipment can trip offline. This problem is mostly associated with voltage sags / dips and swells. Voltage sags / dips are momentary decreases from the nominal voltage value. Voltage sags / dips are typically caused by abrupt increases in loads like short circuits or faults, motors starting, or electric heaters turning on; sags / dips can also be caused by abrupt increases in source impedance, like a loose connection.

Voltage swells are almost always caused by an abrupt reduction in load on a circuit with a poor or damaged voltage regulator, although they can also be caused by a damaged or loose neutral connection. When equipment trips offline, telecom customers can lose their service, costing the telecom money every minute the equipment is off line.

Equipment locking up

Computer equipment can lock up and the data can get garbled due to transient voltages. Large enough transient voltages can also damage equipment. These voltages are abrupt short duration changes in voltage (less than 1 cycle).

Generally, there are two different types of transients:

  1. Low frequency transients with frequency components in the few-hundred-hertz region, typically caused by capacitor switching
  2. High-frequency transients with frequency components in the few-hundred-kilohertz region, typically caused by lightning and inductive loads

Transients not only can cause equipment to malfunction and fail, they can also cause insulation to break down, leading to premature failures in transformers.

Harmonics cause telecommunications equipment to malfunction

Harmonics can cause computer equipment to lock up or data to become garbled. It can also cause the neutral wire to overheat. Linear loads, like incandescent lights and motors draw current equally throughout the waveform. Non-linear loads found throughout telecommunications equipment, such as switching power supplies, draw current only at the peaks of the wave. It is these non-linear loads that cause harmonics.

Electrical noise disrupts data signals

Electrical noise can disrupt data-carrying signals. Noise can be electromagnetically coupled onto signal lines from power lines. Power systems transmit very high energy. Telecommunications systems transmit data at low power. Even though telecom systems are designed to reject a good amount of interference, these high power lines can cause poor transmission efficiency and disruptions. Power lines and telecom cables often run close together causing electromagnetic coupling and noise on the telecom cables.

Telecommunication services are judged by the reliability and quality of their services. Power Quality phenomena can cause poor data transmission rates; disrupt transmissions and cause equipment malfunctions and failures. The reliability and quality of a telecommunication system is only going to be as good as its weakest link.

Telecommunications service interruptions not only generate immediate costs; such as customer claims, service agreement claims, contracted technician troubleshooting hours and equipment repair costs, but also have further reaching consequences. These consequences can be seen as the impact on a service provider’s quality and reliability reputation. This can have an even far greater cost than the immediate effects of the service disruptions.

A telecommunications company can save money, improve quality and reliability by periodically monitoring their incoming power quality and their energy usage. By owning a simple and easy-to-use power quality device, telecom companies can perform their own periodic assessments without the cost of employing outside service companies to perform these tests.