S9407-AB-HBK-010 Datasheet, PDF (120/276 Pages) Glenair, Inc. – HANDBOOK OF SHIPBOARD ELECTROMAGNETIC SHIELDING PRACTICES

S9407-AB-HBK-010, Rev. 2
The latest issues of MIL-E-16400H(NAVY), MIL-STD-1399(NAVY) Section 300(A), and MIL-
STD-461(C) specify limits for leakage current and the size of line-to-ground filter capacitors. These
limits and other requirements are stated as follows:
a. The leakage current (vector sum of all phases) of the equipment, when EMI filtering is
not required, shall not exceed 5 milliamperes (mA).
b. Where EMI filtering (powerline filters) is required in the user equipment, a line-to-line
configuration is preferred. If a line-to-ground configuration is used for filtering, then the
value of the filter capacitance shall not exceed 0.1 microfarad per phase for 60 Hz
equipment and 0.02 microfarad per phase for 400 Hz equipment. If performance or
operational needs of a user equipment require an electrical ground either solidly or by
means of capacitors which exceed the values stated above, then that equipment shall
be electrically isolated from the power system. Isolation transformers shall be installed
on equipment with EMI filtering whose leakage current is in excess of 30 milliamperes.
When necessary, the isolation transformer shall be part of the equipment configuration.
User equipment considerations are listed below.
a. Equipment purchased by the shipyards for shipboard installation, non-Government
Furnished Equipment (non-GFE), should employ line-to-line filters or internal isolation
transformers as required by the latest issues of MIL-E-16400(NAVY), MIL-STD-1399
(NAVY) Section 300, and MIL-STD-461.
b. For equipment provided to the shipbuilder by the Government, Government Furnished
Equipment (GFE), the shipyards must install in accordance with Installation Control
Drawings (ICDs).
c. If EMI problems are identified during system testing, the installer should become aware
of the problem caused by structure currents and the potential need for low-capacitance-
to-ground filters or powerline isolation transformers. As TDA to the NAVSEA SEMCIP
IEMC Element, NUSC/NLL Code 3431 is authorized to work with the shipyard in
formulating a specific recommendation.
d. To further minimize EMI problems of this nature, the armor on power cables should not
be connected to cabinets containing cables assigned an "S" category in accordance
with this section.
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