Voltage Regulator vs. Booster Bank

[saladhawks]

My local utility has both overhead voltage regulators and booster banks installed on a permanent basis (visible by attached signs). It is my understanding that booster banks should only be used on an emergency basis. Since the booster banks I have seen are being used on a permanent basis, what factors would cause a utility to pick a booster bank over a voltage regulator or vice versa?

 

[wareagle]

A utility booster will be rated in amps and % boost. You may see a booster rated a 100 amps and 6% boost. The booster
has several tap positions that will raise the voltage in incremental steps. It can also step the voltage down to the
incoming voltage level.
A regulator can raise or lower the voltage depending on the settings. The regulator may be able to regulate the voltage
+ or - 10% in 5/8% increments. May utilities will use a booster to maintain voltage levels because they are cheaper.