MIL-DTL-917 Electric Power Equipment, Basic Requirements ForThis specification covers the basic requirements applicable to the design, materials, and construction of naval shipboard electric power equipment \(exclusive of communication equipment, information technology \(IT\) equipment, and combat systems [fire control and weapons control equipment]\). Unless otherwise specified herein, the electric equipment developed for shipboard use under the requirements of this specification are limited to a maximum 450 volt \(V\) alternating current \(AC\) and a maximum 1,000 V direct current \(DC\). This equipment is intended for use on surface and submarine naval vessels \(see 6.2\).

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MIL-DTL-917F(SH)

3.13.4.1 Resistor networks. Resistor networks-fixed film shall be in accordance with MIL-PRF-83401.

3.13.5 Capacitors. Capacitors shall be chosen and applied using the guidance in MIL-HDBK-198 as modified

by the additions, limitations, and restrictions specified herein and in the applicable equipment specification

(see 6.2). For radio interference suppression capacitors, see 3.2.16. Capacitors containing PCBs shall not be used.

3.13.5.1 Fixed tantalum (solid electrolyte). Fixed tantalum (solid electrolyte) capacitors shall be in accordance

with MIL-PRF-39003. These capacitors may be used for applications where their voltage ratings are applicable and

where the AC voltage component does not exceed 5 percent of the DC voltage rating. All capacitors with pigtail

leads shall be supported by means other than their leads.

3.13.5.2 Fixed tantalum (liquid electrolyte). Fixed tantalum (liquid electrolyte) capacitors requiring large

capacitance values where close tolerances are not an important factor shall be hermetically sealed in accordance

with MIL-PRF-39006. Where physical space restraints require smaller sized capacitors, sintered anode, wet

electrolyte tantalum capacitors in accordance with MIL-PRF-39006/22 may be used. Otherwise, sintered anode,

wet electrolyte tantalum capacitors shall not be used. All capacitors with pigtail leads shall be supported by means

other than their leads.

3.13.5.3 Fixed ceramic-dielectric (temperature compensating). Fixed ceramic-dielectric (temperature

compensating) capacitors shall be in accordance with MIL-PRF-20. The widest possible capacitance tolerance and

the least stringent temperature coefficient commensurate with the requirements of the circuit application shall be

used. These capacitors are intended primarily for use in circuits where compensation is necessary for variations in

capacitance due to temperature and in bypass and coupling applications. The use of low capacitance [less than

100 picofarad (pF)] capacitors with temperature coefficient of capacitance tolerance of �60 parts per million or less,

shall require approval of the contracting activity.

3.13.5.4 Fixed ceramic-dielectric (general purpose). Fixed ceramic-dielectric (general purpose) capacitors

shall be in accordance with MIL-PRF-39014. These capacitors are intended for use as bypass, filter, and coupling

capacitors where changes due to temperature can be tolerated.

3.13.5.5 Variable ceramic-dielectric. Variable ceramic-dielectric capacitors shall be in accordance with

MIL-PRF-81. These capacitors are intended for operation in circuits where periodic adjustments are required.

3.13.5.6 Variable air-dielectric (tuning). The nominal spacing between opposing plates of air-dielectric

capacitors shall be not less than 0.008 inch, unless specifically approved. In all cases where a nominal spacing of

less than 0.012 inch has been approved, the capacitors shall be enclosed in a dustproof case. The capacitors shall be

constructed of corrosion-resistant material or shall be protected against corrosion. The plates of all capacitors shall

be free from grease, dust, dirt, and metallic burrs. As installed in the equipment, all capacitors shall withstand,

without breakdown, at least 500 Vrms, 60 Hertz (Hz) applied between opposing plates. For variable capacitors, this

breakdown voltage shall hold for all relative positions of rotor and stator plates. The rotors of all variable

air-dielectric capacitors shall be adequately supported and shall make a low resistance contact with the connectors.

3.13.5.7 Fixed supermetallized plastic film dielectric. Fixed supermetallized plastic film dielectric capacitors

(hermetically sealed in metal cases) shall be in accordance with MIL-PRF-83421.

3.13.6 Switches. Switches shall be selected so that rated currents and voltages (make, break, carry) are not

exceeded in the intended application, as well as for their ability to withstand the shipboard environments.

Momentary contact switches are preferred for panel controls. Snap action switches are preferred for power circuit

interruption. Detent action switches are suitable for meter and circuit selection. The switches selected shall

conform to one of the specifications specified in 3.13.6.1 through 3.13.6.11, as applicable.

3.13.6.1 Toggle switches. Toggle switches shall be in accordance with MIL-DTL-3950.

3.13.6.2 Sensitive switches. Sensitive switches shall be in accordance with MIL-PRF-8805 and shall not be

used for applications above 125 V or 50 VA.

3.13.6.3 Push (snap action) switches. Push (snap action) switches shall be in accordance with MIL-PRF-8805

or MIL-DTL-2212.