Quantcast Chapter 3. Transmission and Distribution Substations

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TM 5-684/NAVFAC MO-200/AFJMAN 32-1082
3-4. Substation security.
3-1. Type of substations covered.
In addition to the personnel safety hazards men-
This chapter includes a transmission and distribu-
tioned above, an electrical substation presents an
tion substation which is an assemblage of equip-
attraction to would-be vandals, dissidents, or other
ment for purposes other than generation or utiliza-
belligerents. For these reasons, good security is a
tion, through which electrical energy in bulk is
basic requirement. All means of access to substa-
passed for the purpose of switching or modifying its
tions, including buildings and yards, will be kept
locked when unoccupied and secure when occupied
3-2. Electrical system relationship.
by authorized personnel.
A substation is an integral and vital part of an
3-5. Periodic inspections of substations.
electrical system. It does not exist independently of
An inspection checklist, tailored to a specific substa-
the rest of the system, though it is usually designed
tion and containing all items to be checked, is rec-
so that a failure of a single component will not
ommended. Monthly visual and yearly infrared in-
interrupt loads, except for switching times. Such
spections of the entire substation are recommended.
interruption may force greater than normal loads to
be carried by other components of the station while
3-6. Visual inspections of substations.
repairs are being made. Most substations are de-
Visual inspections should include the total substa-
signed so they do not require attendant personnel
tion area including the site, the control house, and
on a continuous basis. Supervisory control and data
all equipment and structures. The energized sub-
acquisition (SCADA) systems, where provided, al-
station should be inspected from ground level, to
low monitoring at a central point.
ensure adequate safety clearances from energized
3-3. Substation safety concerns.
parts. Binoculars should be used to view buses and
other equipment located on structures. Special care
Substations present a potential safety hazard, ow-
should be used when ground connections are
ing to the large amount of energized conductor sur-
checked, since a high voltage could develop across
face concentrated in a relatively small area. In gen-
any gap created between a ground cable and a piece
eral, only portions of an entire substation can be
de-energized, although scheduled outages may be
of equipment, particularly under fault conditions.
required for equipment which can not be bypassed
For this reason, ground connections shall not be
or worked on while energized. All inspecting and
removed for any reason while the substation is en-
repairing personnel must be thoroughly trained.
The following requirements are minimum:
3-7. Infrared inspections of substations.
a. Familiarity with operating procedures, protec-
tive and interlocking schemes, and the equipment
All matter emits infrared rays in proportion to its
capabilities at the specific substation.
b. Knowledge of the proper use of safety equip-
a. Method. An infrared detecting device can be
ment, first aid procedures and equipment, and
used to determine loose connections, overloading of
equipment grounding techniques.
conductors, localized overheating in equipment, or
c. Access to safeguards such as danger signs, tem-
similar conditions before they become serious. Some
porary barriers, protective clothing, tools and pro-
equipment is sensitive to a fraction of a degree.
tective equipment, and all safety manuals and
Infrared inspection can be done from a distance,
rules. Procedures should clearly indicate insulating
since contact with the item being measured is not
requirements and working clearances for any cat-
required. Substation equipment, such as bare bus,
egory of energized-line maintenance employed.
disconnect switches, and connections, can be
d. Keeping proper inspection records and check-
checked without being de-energized. The inspection
is made by aiming the infrared detector at various
lists so that observed defects or improper conditions
areas of the substation and noting where the hot
not immediately repairable will be promptly cor-
spots are.


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