Protection But No Energy Savings

Transient Voltage Surge Suppressors (TVSS) are designed to protect electrical equipment from transient voltage surges. They typically do a good job of that; however, some TVSS manufacturers and distributors claim their products also save energy. Members asked us about these claims, so we investigated further.

What Causes Voltage Surges?

In an ideal world, electricity that feeds your equipment would be a nice, smooth 60-Hz sine wave, where the voltage alternates between its peak positive and negative values as shown in the figure below. In the real world, electrical equipment in modern commercial and industrial facilities is subject to a lot of electrical noise, either inside the plant or from external sources.

Voltage sags are caused when large electrical loads start and stop. Electronic devices with switch-mode power supplies feed harmonic noise into the line; natural events like lightning can cause surges; and even equipment Jackson EMC installs to protect the electric distribution system such as reclosers, circuit switches and capacitor banks may cause transients and surges.

In addition, complex modern equipment with electronic control flexibility tends to be more sensitive to voltage surges, sags, and electrical noise.

Transients are short disturbances in power, usually lasting less than 10 microseconds. Because most transients are so rapid, they usually carry very little energy, but can damage sensitive electronic equipment.

Voltage surges typically last longer than transients, between 10 microseconds to 1 millisecond, and carry enough electricity to severely damage electrical equipment.

Equipment Options

There's a wide variety of protective equipment designed to reduce the effects of power quality disturbances; the most common being surge protectors sold for computer and electronic equipment. Many types of TVSS devices are available, from equipment designed to protect an individual piece of equipment to systems designed to protect an entire plant. Make sure the equipment you buy is UL listed for standard 1449. TVSS equipment holds surge and transient voltages at safe levels while diverting these disruptive currents away from protected equipment. The equipment's response time, operating voltages, and maximum energy capacity vary. Higher levels of protection typically cost more money.

Before selecting equipment, evaluate your requirements and options carefully. While no device can provide complete protection, most listed TVSS equipment does a good job of limiting transients and surges.

Buyer Beware

Some TVSS manufacturers and distributors claim their equipment saves energy. One manufacturer's Web site discusses energy savings and offers guaranteed savings. There are also claims that transients cause cumulative damage to insulation resulting in potential energy loss over an extended period of time.

There is no evidence to support these claims. E-Source, the Electric Power Research Institute, and power quality engineers' investigations all dispute these claims. The investigation results also cite the cumbersome guarantee process required to submit a claim, along with potential guarantee loopholes that may make collection difficult.

This is a case of buyer beware. Jackson EMC recommends TVSS equipment for what it's designed to do — help protect equipment from surges and transients. However, don't expect to save energy with these devices.

Want more information or details? Contact your Jackson EMC Commercial and Industrial representative.