NPFC - MIL-R-5757

RELAYS, ELECTROMAGNETIC, GENERAL SPECIFICATION FOR

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Organization:	NPFC
Publication Date:	22 March 1982
Status:	inactive
Page Count:	42

scope:

This specification covers the general requirements for electrical relays with contact ratings up to and including 10 amperes for use in electronic, communication, and other type applications (see 6.1).

CAUTION: The use of any coil voltage less than the rated coil voltage will compromise the operation of the relay.

Relays shall be classified as specified herein.

The enclosure design is identified by a single digit in accordance with table I. TABLE I. Enclosure design.

Symbol Type ------------------------------------------------------------------------ 3 - - - - - - - - - - Sealed (other than hermetically) 4 - - - - - - - - - - Hermetically sealed (A relay contained within an enclosure that is sealed by fusion to insure a low rate of gas leakage-This usually refers to metal-to-metal, metal to ceramic, or metal to glass sealing.)

The vibration characteristic is identified by a single digit in accordance with table II. TABLE II. Vibration characteristic.

Maximum Symbol acceleration Frequency value range --------------------------------------------------------- Hz 1 - - - - - - - - - - 0.060" D.A. 10 to 55 2 - - - - - - - - - - 10G 10 to 500 3 - - - - - - - - - - 15G 10 to 2,000 4 - - - - - - - - - - 20G 10 to 2,000 5 - - - - - - - - - - 30G 10 to 3,000 6 - - - - - - - - - - Random (see 3.1) 50 to 2,000

The temperature range is identified by a single letter in accordance with table III. Beneficial comments (recommendations, additions, deletions) and any pertinent data which may be of use in improving this document should be addressed to: Naval Electronic Systems Command, ATTN: ELEX 8111, Department of the Navy, Washington, D.C. 20360 by using the self-addressed Standardization Document Improvement Proposal (DD Form 1426) appearing at the end of this document or by letter. TABLE III. Temperature range.

Symbol Range ------------------------------------------------ °C A - - - - - - - - −55 to +85 B - - - - - - - - −65 to +125

The shock type is identified by a single digit in accordance with table IV. TABLE IV. Shock type.

Symbol Shock type (in accordance with MIL-STD-202) -------------------------------------------------------------------- 1 - - - - - - - - - - 50G (test condition A method 213) 2 - - - - - - - - - - 75G (test condition B method 213) 3 - - - - - - - - - - 100G (test condition C method 213) 5 - - - - - - - - - - High-impact (method 207)

The military part number shall consist of the letter "M", the basic number of the specification sheet, and an assigned dash number as shown in the following example (see 3.1, 6.2.1, and 6.2.2):

EXAMPLE:

intended Use:

Relays conforming to this specification are intended for use in dc or ac (single or polyphase) electronic and communication equipment as a means of controlling the making and breaking of circuits for electrically operated equipment and devices. Their principal areas of application are for aircraft, missiles, spacecraft, and ground-support electronic and communication equipment. This does not preclude the use of these relays in other military applications. This specification excludes thermal and completely solid state type relays. For established reliability relays, see MIL-R-39016 "Relays, Electromagnetic, Establlished Reliability, General Specification For". Consult MIL-STD-1346, Relays Selection and Application, as to selection and application.

The contact ratings of relays covered by this specification are based on load endurance tests which establish the relay capability to switch rated loads, minimum loads from 100 mA up to rated loads, and low level loads. Performance may be unsatisfactory when contact current or voltage differs substantially from the rated values.

Users of relays are cautioned that a 115/200 V rating implies that the relay is designed for use in a 3 phase system. The contacts may not be capable of switching 200 V. For cirucit applications requiring relay contacts to interrupt 200 volts, the manufacturers of the relay should be consulted.

The current range within which the contact arc intensity is insufficient to consistently burn away carbonaceous materials on contact faces. The carbonaceous deposits are a result of breakdown of gases within a relay which originates from contaminants such as cleaning fluids, outgassing of materials within the relay, etc., which are broken down to carbon within the contact arc.

NOTE: Because intermediate current testing is exceedingly time consuming and because 50,000 operations of test cycles is sufficent to prove compliance capability, relays can be safely used for 100,000 operations applications.

Relays should not be used in 3-phase load transfer applications unless a 3-phase ac load transfer rating specifying both current and system voltage is specified.

NOTE: When two position relays (typically with form C contacts) are considered for transferring loads from one source to another, even relays with large contact gaps and slow operate and release times should be properly derated. Reliance should not be misplaced on sophisticated relay coil control circuitry, since the transfer time depends only on the operate and release times of the relay. Transfer relay contacts shall not be used to ground load in one position and to 115 volt terminal in other position. Transfer relay contacts shall not be used to transfer load between phases, nor between unsynchronized ac sources.

Contacts shall not be paralleled on the assumption that doing so will increase their switching capacity. Being paralleled for the sake of redundancy may result in make-before-break instead of break-before-make, due to one transfer contact operating slightly ahead of the other.

When latching relays are installed in equipment, the latch and reset coils should not be pulsed simultaneously. Coils should not be pulsed with less than the nominal coil voltage and the pulse width should be a minimum of three times the specified operate time of the relay. If these conditions are not followed, it is possible for the relay to be in the magnetically neutral position.

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