PZM Solutions — Lowering High Reg Ops
Protection Zone Management (PZM) software offers a unique
program that not only simplifies your inspection program, but
gives you valuable feedback to improve your electrical system.
PZM has created
Alerts in our
software to provide utilities information they can act on to
improve their system. PZM Solutions are ideas
we have that utilities can use to respond to alerts and make
meaningful improvements to their system.
Feedback control theory illustrates you can't control anything
without feedback and response. Management guru Peter Drucker
says what gets measured, gets managed. PZM uses your inspections
to provide the important feedback and measurements needed to
control and manage your system. PZM Solutions are ideas for a
response. Using this process, you will be able to stay in
control of your operation.
PZM Reg Ops Alert
PZM Reg Ops Alert feature measures how many times your regulator
changes taps and calculates a monthly and annual average based
on the number of operations between inspections.
A high regulator ops score indicates a regulator that could be
operating too much.
Why should a utility reduce regulator operations:
Reducing operations extends the maintenance intervals of
Reducing operations will extend the life cycle of voltage
Voltage Regulator Operation
The following three settings are what a voltage regulator
controller uses to control voltage:
This sets the desired voltage at the output of the regulator. It
is set on a 120V basis. Generally, the output is set higher than
120V to account for voltage drop downstream, with the goal of
delivering 114V to 126V at all loads, or from 95% to 105% of the
120V basis. A setpoint programmed at 123V would deliver a 102.5%
Voltage regulators make voltage changes in steps. Typically,
each step moves the voltage by 0.625%. Because of these step
increases and step decreases, it is important to program an
acceptable range of voltage for the regulator to operate. This
acceptable range is called the voltage band. The voltage band is
also programmed on a 120V basis. The bandwidth setting is the
total range, and half the range will be below the setpoint, and
half will be above the setpoint. With the voltage setpoint
programmed at 123V and the bandwidth programmed at 2V, the
acceptable voltage range would be from 122V to 124V or 101.67%
to 103.3%. If the regulator output voltage is operating in this
acceptable range, it is considered 'in band,' and if the output
voltage is outside of this range, it is considered 'out of
band.' A bandwidth programmed between 1 and 3 volts is typical.
Voltage regulators should always be programmed with a time delay
before responding to an 'out of band' voltage level. This time
delay will ensure the voltage regulator doesn't overreact to a
voltage is out of band for a short duration. Changing voltage
requires a tap changer operation and causes some contact wear,
so it is best not to have a regulator operate if it is a quick
For example, if a large motor starts on a distribution feeder,
the inrush current might cause the voltage to dip momentarily
and recover. Raising the voltage will not affect the motor
start-up, so it is best not to operate and cause undue wear to
the regulator. A time delay programmed between 20-60 seconds is
typical. Time delay with cascading regulators is an important
consideration when programming time delay. Rural feeders are
typically several miles long and may require several regulators
to maintain acceptable voltage along the line's entire length.
These are called cascading regulators (See figure below).
Voltage regulator time delay must be coordinated when there are
cascading voltage regulators. The time delay should increase as
the distance from the source increases. This allows the first
regulator a chance to correct the voltage first. Typically the
time delay between cascading regulators should be at least 15
PZM Solution — Reducing Regulator Operations
There are two main strategies to lower voltage regulator
operations, increasing the bandwidth, and increasing the time
Increase the Bandwidth
Programming a larger bandwidth increases the acceptable range of
voltage at the output of the regulator. This will keep the
regulator 'in band' longer. By staying in band longer, the
voltage regulator will operate less often. When increasing the
bandwidth, ensure the upper band doesn't allow a voltage out of
compliance with your utility standards (typically 126V or 105%).
The upper band is the setpoint + ½ the bandwidth.
Extend Time Delay Setting
Programming a longer time delay will reduce the operations on a
voltage regulator. The time delay clock begins when the voltage
crosses the band edge and remains 'out of band.' If the voltage
remains 'out of band' for the programmed time delay, the voltage
regulator will operate until it brings the voltage back 'in
band'. When adjusting the time delay on a rural feeder with
cascading regulators, be sure to maintain time delay
Additional Ideas to Lower Operations on Voltage Regulators
PZM Solution Idea — Add capacitor banks
Adding capacitor banks can be used to reduce inductive VAR flow
and improve the voltage on a feeder. This voltage improvement
can reduce voltage regulator operation.
PZM Solution Idea — Reduce or Balance Loads
The idea behind reducing or balancing loads on a feeder is to
lower the current flow, decrease the voltage drop, and improve
the feeder's voltage. This voltage improvement can reduce
voltage regulator operation. Reducing load is not always
possible if no tie point exists to relieve the load on a feeder.
A capital project may be required to build a new feeder to
handle some of the load.