Why does it take so long to switch off power to a substation or isolate a specific part of a power grid system are they not all remotely controlled from a central manned control room?
Often, it depends on whether the substation is under "grid"
authority or "distribution" authority. Almost all "grid"
substations, being operated at High or Extra High voltages (138Kv -
765Kv), ARE remotely controlled via a SCADA system, however many
"distribution" substations, with their attendent lower (4Kv - 25Kv)
voltages have minimal or no remote control capability, depending on
the size and location of the distribution substation. Large cities
with distribution substations will likely have SCADA control
however the smaller the city, the less chance of having SCADA
control of the substations contained therein. The question is "why
would not all substations be remotely controlled?". In one word,
cost. SCADA systems are relatively expensive (although SCADA
hardware cost has been decreasing over the last 20 years). Another
reason is the cost of trained manpower to monitor and control the
lower voltage substations. Control room operations are demanding,
and pressure filled. It takes a technically savvy individual,
backed with intensive specialized training to competently operate a
series of substations remotely.