For grounding see figure 9-3.
US ARMY Corps of Engineers
Figure 8-5. Secondary Unit Substation Transformer Installation.
turing, Processing, Distribution in Commerce, and
to meet the criteria contained in chapter 4, as
a. Mineral oil. Mineral oil transformers will be
8-4. Transformer Dielectrics.
used for outdoor installations only. Mineral oil is
In addition to the guidance listed below, the
the preferred dielectric for outdoor installations.
b. Less-flammable liquid. Less-flammable liquid
dielectric system will be selected based upon cost,
doors, and will be installed in accordance with
available space (liquid-filled units tend to have
MIL-HDBK-1008A. Acceptable less-flammable
larger front-to-back dimensions, due to their radia-
liquids are limited to high-molecular-weight hydro-
tors, than dry-type units), and the HVAC system
c a r b o n s and dimethyl silicone. Where less-
in the room (dry type units tend to have higher
flammable liquid transformers are proposed, a cost
losses than liquid-filled units). All dielectrics speci-
analysis will be provided which covers the accept-
tied must meet the requirements of 40 CFR Part
able alternatives and indicates that the most cost
761; "Polychlorinated Biphenyls (PCBs), Manufac-