Applying a voltage regulator/power conditioner is simple. As with any electrical product, care must be taken to ensure that all national, state and local codes are observed, and that the specifying, installation, operation and maintenance of voltage regulator/power conditioner are conducted by qualified professionals.


The first rule in applying a voltage regulator/power conditioner:
Place the voltage regulator/power conditioner between the source of the power problem and the equipment to be protected. A corollary to this rule is placing the voltage regulator/power conditioner immediately ahead of the equipment to be protected in order to provide maximum protection. The sources of power quality problems can be external, internal or both.

External causes include undervoltage, sags, surges or other problems initiated on the electrical transmission or distribution network outside the end user’s facility. The main electrical service entrance is the point of entry into the facility.

Internal causes tend to be sags and undervoltage created by large electrical loads or loads with high inrush current. Motors, magnets, transformers and welders are examples of internal loads that frequently cause power quality problems that can affect other equipment.

For example, a facility subject to chronic undervoltage because of its location in a large industrial park may install a new CNC tool. When the tool starts, the large inrush current depresses the already low voltage to the point that other equipment malfunctions. This is a typical example of external and internal conditions combining to cause a symptomatic power quality problem.

The following are reasons to apply a voltage regulator/power conditioner:

  • Red lines indicate poor power delivery
  • Green lines indicate protected power delivery
  • Red and green lines indicate power delivery that can be intermittently good and poor

Maximum Protection

The optimum application is placing a dedicated voltage regulator/power conditioner in front of each device to be protected. In this scheme, each device is protected from external and internal power-quality problem sources . It also provides the highest degree of reliability because of the multiple units.


Maximum Protection II

Here, again, is the optimum application as loads B and C are protected from external and internal power quality problems created by load A.


Protection from External Problems

In this common application, a voltage regulator/power conditioner is sized to protect multiple loads from external power quality problems. Voltage regulator/power conditioner costs are minimized by using a larger single unit. If existing wiring is used, this may be the most inexpensive application.

The downside of this application is lack of protection from internally generated power quality problems (see next example). This application is often used when there are no large or problematic internal loads. Typical applications include installation at service entrances or ahead of distribution panels.


Unprotected from Internal Problems

A voltage regulator/power conditioner is sized to protect multiple loads, but in this case, load A is the source of an internal power quality problem. Typically, this problem is a sag each time the load is started. While the voltage regulator/power conditioner is correcting for external problems, internal problems generated downstream of the voltage regulator/power conditioner go uncorrected. In other words, loads B and C are protected from external problems, but are at risk from those generated by load A.

See also: Power Conditioning Terms


Other Application Considerations


A bypass can serve two purposes: 1) to divert power around a portion of the unit, or 2) to isolate the unit.

When used in the first case to divert power around a portion of the unit, the bypass may be acting to protect the unit itself from extraordinary conditions or provide power downstream if a portion of the unit malfunctions or is temporarily inoperable. For example, if UPS batteries are drained and cannot provide power to the load, many UPSs go into “bypass mode,” providing raw, unconditioned power to the load so it can remain online. (See electronic bypass.)

When used to isolate a unit (generally used for larger units), a bypass made of circuit breakers or disconnect devices electronically isolate incoming and outgoing “sides” of the voltage regulator/power conditioner from the system. The unit can then be safely isolated for maintenance while downstream devices receive unconditioned power to remain online.

Step Down – Step Up

Some voltage regulator/power conditioners are capable of taking incoming power at one voltage level and providing it at a lower voltage level at the output (for example, from 480 volts to 208 volts). This ability to “step down” the voltage can eliminate the need for a separate transformer to change the voltage to the proper level for the downstream devices. In some cases, a “step up” might also be useful.

Wiring Connections

DeltaSingle phase voltage regulator/power conditioners have simple input and output connections (generally, two “hot” lines in and two “hot” lines with a new ground coming out). In some cases, a single-phase unit might be supplied with a line coming from an extra “tap” on the secondary in order to provide single-phase output voltages at two convenient levels, such as 240v and 120v. This arrangement is sometimes referred to as a “split phase.”

WyeVoltage regulator/power conditioners in three-phase applications typically utilize a “delta” input and a “wye” output, which is the most common arrangement in industrial and commercial applications. The “wye” output is particularly useful since it allows output voltage at two different levels (line-to-line and line-to-neutral) and provides a new ground reference for downstream devices.