SAE ARP 4005C-2017 Selection and Application of Electro-Mechanical Relays for Proper Performance.pdf

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1、_ SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising there

2、from, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions. Copyright 2017 SAE International All rights reserved. No part of this p

3、ublication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: +1 724-776-497

4、0 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/standards.sae.org/ARP4005C AEROSPACE RECOMMENDED PRACTICE ARP4005 REV. C Issued 1989-04 Revised 2017-11 Supersedi

5、ng ARP4005B Selection and Application of Electro-Mechanical Relays for Proper Performance RATIONALE To update industry reference documents as needed and make minor editorial and clarifications to the ARP text. TABLE OF CONTENTS 1. SCOPE 3 2. REFERENCES 3 2.1 Applicable Documents 3 2.1.1 ECA Publicat

6、ions 3 2.1.2 IEEE Publications 3 2.2 Definitions . 3 2.2.1 Terms 3 3. APPLICATION INFORMATION 4 3.1 General 4 3.2 Relay Selection and Application . 4 3.2.1 On-Off Load Control 5 3.2.2 Transfer Operation 7 3.2.3 Multiple Relay Operation . 9 3.2.4 Coil Transient Suppression . 10 3.3 Relay Contact Conf

7、igurations . 10 3.4 Relay Misapplication . 10 3.5 Relay Application Checklist . 14 4. CONTACT LOAD CAPABILITIES . 15 4.1 Transformer Loads 16 4.2 Power Switching 16 4.3 Low Level Loads Switching . 16 4.4 Dry Circuit Switching . 16 4.5 Intermediate Current Switching . 17 4.6 Alternating Current 17 4.

8、7 Arcing and Transient Loads 17 4.8 Overload Capability Considerations 18 SAE INTERNATIONAL ARP4005C Page 2 of 23 5. COIL OPERATION DATA . 18 5.1 Operate Voltage (Coil) 18 5.1.1 Rated Voltage (Coil) 19 5.1.2 Abnormal Voltages (Coil) 19 5.2 Operational Control of Relay (Coil) . 19 5.2.1 On/Off of Squ

9、are Wave Control of Relay (Coil) 19 5.2.2 Ramp Control of Relay (Coil) 19 5.2.3 Contact Load Effect on Control Voltage (Coil) 20 5.3 Diode and Zener Diode Effects on Operation of Relay (Coil) . 20 5.4 Pickup Operation of Relay (Coil) . 20 5.5 Hold Operation of Relay (Coil) 20 5.6 Dropout Operation o

10、f Relay (Coil) . 21 5.7 Coil Voltage Cautions 21 6. HANDLING CONSIDERATIONS 21 6.1 General 21 6.2 Sources . 22 6.3 Forming or Cutting Contact Leads 22 6.4 Automatic Insertion Equipment . 22 6.5 Vapor Soldering or Surface Mounting . 22 6.6 PCB Cleaning 22 6.7 Relay Storage . 23 6.8 Mounting Pads 23 6

11、.9 Pretinning 23 7. NOTES 23 7.1 Revision Indicator 23 Figure 1A Improper circuit design 6 Figure 1B Properly designed circuit . 6 Figure 1C Improper circuit design 6 Figure 1D Properly designed circuit . 6 Figure 1E Not recommended relay open ground 7 Figure 1F Preferred design, two controlled with

12、 no adverse interaction on dropout . 7 Figure 1G Improper motor braking . 7 Figure 2 Polarity reversal, form C contacts . 8 Figure 3 Center off polarity reversal, form K contacts . 8 Figure 4 Concurrent relay operation, cascade method . 9 Figure 5 Concurrent relay operation, parallel method . 9 Figu

13、re 6 Symbols and markings for contact and coils 11 Figure 7 Contact shunting circuits . 18 SAE INTERNATIONAL ARP4005C Page 3 of 23 1. SCOPE 1.1 This SAE Aerospace Recommended Practice (ARP) provides information to guide in the selection of electromechanical relays to be used in electrical/electronic

14、 circuits for application in aerospace, ground, and shipboard systems to achieve proper performance. 1.2 Relays intended for use in aerospace industry and military applications are substantially different from those produced for industrial applications. Most industrial relays are designed so that th

15、e user can convert contact sets from NO to NC (and vice versa); add and replace auxiliary contact sets; change or replace coils; use coils on systems up to 600 V 50 to 60 Hz and expect relays to last for many operations. Typically, aerospace relays are designed to be nonrepairable with fixed contact

16、 configurations and generally for systems not exceeding 200 V and 400 Hz. These relays are generally for 28 V DC, and 115 V AC 400 Hz applications. The applicable system requirements are typically in accordance with MIL-STD-704 and RTCA-DO-160 (Radio Technical Commission for Aeronautics). These rela

17、ys are high-performance, low volume and low mass types, when compared to industrial types, and have little margin to tolerate an application or selection error. 2. REFERENCES 2.1 Applicable Documents The following publications form a part of this document to the extent specified herein. The latest i

18、ssue of SAE publications shall apply. The applicable issue of other publications shall be the issue in effect on the date of the purchase order. In the event of conflict between the text of this document and references cited herein, the text of this document takes precedence. Nothing in this documen

19、t, however, supersedes applicable laws and regulations unless a specific exemption has been obtained. 2.1.1 ECA Publications Available from ECA, 2500 Wilson Boulevard, Arlington, VA 22201, Tel: 703-907-8024, Engineers Relay Handbook 2.1.2 IEEE Publications Available from IEEE Operations Center, 445

20、 Hoes Lane, Piscataway, NJ 08854-4141, Tel: 732-981-0060, www.ieee.org. IEEE 315-1975 2.2 Definitions 2.2.1 Terms For a list of common terms used in the rating and design application of relays, refer to the ECA Engineers Relay Handbook. For relay definitions and terminology, refer to ANSI C83.16. SA

21、E INTERNATIONAL ARP4005C Page 4 of 23 3. APPLICATION INFORMATION 3.1 General This section contains general guideline information to assist the application engineer or circuit designer in choosing the appropriate relay. 3.2 Relay Selection and Application CAUTION: The use of any coil voltage other th

22、an the rated coil voltage may compromise the operation of the relay. Choosing the proper relay depends primarily on matching the relay to the load, power supply, and environment. Selection should be limited to items that meet the following requirements. CAUTION: When latching relays are employed in

23、a circuit, the latch and reset coils should not be pulsed simultaneously. Coils should not be pulsed with less than the nominal voltage and the pulse width should be at least three times the specified operating time of the relay. a. Contacts must be rated for the load. Current rating, type of load (

24、resistive, lamp, motor, inductive, and so forth), impedance range, voltage rating, DC or AC, frequency, single phase or polyphase, load balance, and type of switching or transfer should all be considered. Each of the following switching and transfer functions places a different requirement on the re

25、lay contacts and must be considered when selecting a relay with the proper contact rating: 1. On-off switching - DC, AC (single phase or polyphase) 2. Motor reversing (AC or DC) 3. Transferring load between phases of same source 4. Transferring load between unsynchronized AC sources b. Power supply

26、characteristics must be taken into account. Voltage regulation, variations in frequency, ripples and spikes, as well as steady state conditions, should be included. If more than one power supply is involved, not only must each be suitable but any interaction between them also should be investigated.

27、 c. When selecting a relay for an application, the coil (or coils) should be rated to insure proper operation under all anticipated conditions. d. Consideration of the environmental conditions anticipated throughout the service life, as well as those expected during storage and transportation before

28、 installing the relays in the equipment, is mandatory. Electrical parameters, environmental factors, mechanical stresses, and proper relay application are among the categories which must be investigated. e. The circuit in which the relay is used, the interlocking feature employed, the wiring harness

29、, and the associated components should all be investigated to assure suitability. f. Plug-in relays, if used, should be types that “lock“ to their sockets and are specifically intended for use with a specified relay. Relays designed to be soldered are not typically suitable for use in sockets. g. Ca

30、re should be exercised in handling, lead forming, and lead cutting of hermetically sealed relays, since extremely close cover-to-frame spacing and fragile glass seals make these types of relays susceptible to physical damage, if not handled properly. Leads should be supported near glass and shear ty

31、pe cutters, not side cutters, used. SAE INTERNATIONAL ARP4005C Page 5 of 23 h. When it is required to provide “safe“ isolation of the relay circuit in the OFF condition, and eliminate an electrical shock hazard, an electromechanical switching device should be placed between the positive terminal of

32、the power source and the relay coil. Proper transistor control of the relay coil requires a stable reference voltage. For example, this can be done by connecting the plus side of the coil to the positive side of the power source. the minus side of the relay coil to the collector of an NPN transistor

33、, the emitter of the transistor to the grounded side of the power source, and the transistor base to the control voltage; for example, MIL-PRF-28776/1. Any switching device controlling the relay coil circuit must be capable of withstanding, without damage, the sum of the maximum coil circuit voltage

34、 and the peak value of transient voltage that results when the coil field collapses. For example, a switch controlling a relay coil that is fed by a 28 VDC line and subjected to a transient voltage suppressed to 42 V must be capable of withstanding 28 V + 42 V, i.e., 70 V surges without damage. i. I

35、n selecting solid state electronic switching devices to control relay coil circuits, care must be used in selecting a solid state device with a leakage current (in the “off“ state) that is sufficiently low to guarantee that the relay will drop out. j. Control of the relay coil circuit by other than

36、step-function switching may invalidate published relay performance properties such as pickup and dropout voltages (latch/reset) and pickup, dropout (latch/reset) times, and bounce times. 3.2.1 On-Off Load Control On-off control of loads is a typical relay function. Where practical, one side of every

37、 load, including relay coils, should be connected to a common line (the grounded conductor of their power supply). All contacts will be on the hot side with respect to the loads. No contact shall be connected to ground. The switching should be done on the hot side of a circuit to prevent electrical

38、shock, to decrease the possibility of circuit malfunction, and to reduce the number of contacts. Figures 1A, 1B, 1C, 1D, 1E, 1F, and 1G illustrate the problems that can be avoided by proper circuit design. a. Figure 1A is an example of a control problem resulting from not connecting all loads to the

39、 same common terminal. With three relays in series across the line, each has approximately one-third voltage available to it continuously. In addition to the power drain, the relays will be sensitive to temperature, vibration, and mechanical shock causing spurious operation. Relay K1 is energized wh

40、en switch A is closed. Relay K3 is energized when switch B is closed. Relay K2 is energized when switch A and switch B are both closed. If switch A is closed and then reopened, relay K1 may remain in the energized mode due to the back circuit through coils K1, K2, and K3. Similarly, relay K3 may sta

41、y energized when switch B is opened. This uncertainty is corrected by the circuit of Figure 1B, in which all voltage is removed from the relay coils to be deenergized. b. Figure 1C - The opening ground lead does not open both relays; it places both in series. c. Figure 1E - Two relays in parallel wi

42、ll interact on dropout; if one relay is much larger, the smaller relay may false cycle. Transient protection on either relay coil will suppress both, whether or not desired. With two relay coils in parallel, if one has an internal series diode and the other is not suppressed, the diode may break dow

43、n from the coil transients on dropout. d. Figure 1G - A common example of poor practice is motor dynamic braking with form C contacts. Contacts may handle run current but often fail to interrupt inrush and cause a line-to-ground fault through the switch. It is improper circuit design to have both li

44、ne and ground on the stationary contacts. SAE INTERNATIONAL ARP4005C Page 6 of 23 Figure 1A - Improper circuit design Figure 1B - Properly designed circuit Figure 1C - Improper circuit design Figure 1D - Properly designed circuit SAE INTERNATIONAL ARP4005C Page 7 of 23 Figure 1E - Not recommended re

45、lay open ground Figure 1F - Preferred design, two controlled with no adverse interaction on dropout Figure 1G - Improper motor braking 3.2.2 Transfer Operation Relays used in transfer operations are subject to greater electrical stresses than relays used for on-off load control. Typical transfer app

46、lications are those in which relays are used to reverse motors, reverse load polarity, or connect alternate power supplies to a load. Form C contact configurations are particularly susceptible to failure in transfer modes. Fast operation of a transfer contact can short circuit a power supply by maki

47、ng contact at one voltage before ionization from a previous voltage has decayed. a. Operate time, release time, contact air gap, spacing between contact poles, type of load, and power supply characteristics are factors that must be considered. Some manufacturers offer relays with form C contacts, pr

48、operly derated, for transfer applications. Because of the uncertainties which arise, even with the best designed circuits, users should be aware of the possibility of failures. The reason may be no more sophisticated than overvoltage applied to the coil, resulting in abnormally fast pickup. Mechanic

49、al interlocking alone may not protect form C contacts used for transfer operations. Figure 2A illustrates polarity reversal of a load by form C contacts. If a contact arc persists for the operate or release time of the relay, the power supply is short circuited. The circuit shown in Figure 2B is preferred. SAE INTERNATIONAL ARP4005C Page 8 of 23 b. Failures can be reduced by using either three-po