1、r y EIA 376 5b 3234b00 0028539 5 4.- =-A /- e h c n 2 iu RETMB STANDARD Pulse Transformers for Radar Equipment RS-176 (Revision of TR-129) December 1956 Engineering Department RADIO-ELECTRONICS-TELEVISION MANUFACTURERS ASSOCIATION EIA 176 56 m I- NOTICE m A; .I RETMA standards are adopted in the pub
2、lic interest and are designed to eliminate misunder- standings between the manufacturer and the purchaser and to assist the purchaser in selecting and obtaining without delay the proper product for its particular need. Existence of such stand- ards does not in any respect preclude any member or non-
3、member of RETMA from manufacturing or selling products not conforming to the standard. Any proposal of recommended standards and practices made by the Association is without any regard to whether or not their adoption may in any way involve patents on articles, materials or processes. By such action
4、, the Association does not assume any liability to any patent owner, nor does it assume any obligation whatever to parties adopting the recommended standards or practices, Published by ELECTRON IC INDUSTRIES ASSOCIATION Engineering Department 2001 Eye St., N.W., Washington, D.C. 20006 COpyright 1966
5、 by Radio-Electronies-Television Manufacturers Association All .riphta reserved Price $1.20 Printed in U.S.A. ,-; EIA 176 5b 3234b00 0028521 3 W -A PULSE TRANSFORMERS FOR RADAR EQUIPMENT (From Standards Proposal No. 515 formulated under tb cognkance of RETMA Engineerhg Committse SQ-4 OB Tramfmers an
6、d Reactors) 1, SCOPE This standard covers iron core pulse transformers for use in radar transmitters and similar equip ment where long life, reliability and continuity of operation are essential. 2. DEFINITIONS Definitions of electrical terms used in this standard shall be in accordanee with those g
7、iven in “American Standard Definitions of Electrical Terms”-ASA#C42-1941. Definitions of terms used in this standard, but not covered by ASA#C42-1941, are given below: 2.1 Pulse Shape Definitions Pulse shape definitions are given in Appendix I. 2.2 Pulse Repetition Frequency The pulse repetition fre
8、quency is the number of times per second that a pulse is transmitted. 2.3 Duty Cycle The duty cycle is the product of the pulse duration and the pulse repetition frequency and repre- sents the time per second during which power is applied to the transformer. 2.4 Loadimpedance The pulse load impedanc
9、e is defined as the ratio of the pulse voltage to the pulse current which flows when the pulse voltage is applied to the load. 2.5 Non-Induced Voltage A non-induced voltage is a voltage which is applied uniformly to an entire winding in such a man- ner that no appreciable potential difference is ind
10、uced along the winding. It may be direct voltage or alternating voltage. NOTE : The filament voltage supplied to the load through a bifilar winding is one example of 8 non- induced voltage. 2.6 Non-Induced Current A non-induced current is a current which flows through a winding of a transformer, but
11、 which is not due to a voltage induced in the transformer. NOTE : The filament current in a bifilar winding is one example of a non-induced current. 2.7 Bifilar Winding A bifilar winding consists of two windings to be operated with no pulse potential between them. A bifilar winding is usually used t
12、o carry filament current to the heater of a tube whose cathode is driven by the transformer. 2.8 Trigger Winding A trigger winding is a winding added to a transformer for the purpose of supplying a relatively low voltage pulse to an external load, usually used for synchronizing purposes. 2.9 Graded
13、Ineulation Graded insulation is a method of construction wherein the insulation to ground is reduced more or less uniformly from the high potential end to the ground (or low potential) end. It is appli- cable to high voltage pulse transformers, where windings are pemnmtly grounded at one end, or ope
14、rate with one end permaneatly connected to a potential of 600 volts or less. RS-176 Page i _. 5m 3. PURCHASE SPECIFICATIONS The purchaser will specify: 3.1 Electrical Requirements 3.1.1 Minimum and maximum pulse duration and the duty cycle for each applied pulse duration, 3.1.2 Primary winding pulse
15、 voltage and pulse current, or primaryto secondary turns ratio; the impedance characteristics of the pulse source. 3.1.3 Number of secondary windings required and the pulse voltage and pulse current of each winding. 3.1.4 Circuit diagram of the modulator and an accurate description of the load or lo
16、ads shall be given, with pertinent non-linear characteristics and with particular emphasis on significant capacitances. 3.1.5 Magnitude, polarity and/or phase relationship of all non-induced voltages and currents for all windings where they occur. NOTE : The total D-C resistance of any bifilar secon
17、dary windings shall be supplied to the pur- chaser by the manufacturer as soon as practicable. 3.1.6 Relative importance of and limitations on : pulse rise time, overshoot, droop, fall time, back- swing and return swing. (It may be necessary for the purchaser to supply a modulator to the manu- factu
18、rer for design checks.) 3.1.7 Unusual requirements or operating conditions, such as intermittent operation. NOTE ; In line-typs modulators, if the load circuit opens, the pulse transformer voltage mag rise to more than twice rated value. If this is a relevant possibility, it shall be specifled by th
19、e purchaser. It may require use of protective means, 3.2 Construction Features 3.2.1 General assembly (For example : Uncased core and coils, end bell, sheet metal encased, dry or liquid filled, hermetically sealed.) NOTE : In specifying construction, cognizance should be taken of requirements impose
20、d by 3.1.2, 3.1.3, 3.3.2, 3.3.3, 3.3.4 and 4.3. 3.2.2 Terminals (For example : leads, screw terminals or solder lugs.) 3.2.3 Mounting (For example : terminal end or opposite end.) 3.2.4 Limiting dimensions and weight. 8.3 Conditions of Operation 3.3.1 Maximum ambient temperature for continuous opera
21、tion. (a) Unless otherwise specified, the maximum ambient temperature shall be assumed to be 60C. 3.3.2 Minimum storage and operating temperature should be -66C unless otherwise specified. 3.3.3 Maximum altitude if more than 6,000 feet above sea level. 3.3.4 Special conditions such as ability to wit
22、hstand vibration. 3.3.5 Other specifications with which the pulse transformer must comply (Army, Navy, etc.). 4. PERFORMANCE STANDARDS a 41 Temperature Rise When tested under standard conditions as described in 6.2, the maximum temperature rise of the transformer winding shall not exceed the limit f
23、or the class of insulation used, as defined by the latest issue of AIEE Standard No. 1. Unless other classes are specifically agreed upon between purchaser and manufacturer, Class A insulation shall be used. - .-f% EIA 176 5b 3234600 0028523 7 RS-176 Page 3 4.2 Winding Voltage With the voltage speci
24、fied in 3.1.2 impressed on the primary winding and with all windings sub- jected to the non-induced voltages and currenb of 3.1.5, the secondary windings shall deliver the voltages specified in 3.1.3 within the limitations of 3.1.6. If turns-ratio is specified in 3.1.2, it shall be maintained within
25、 2% of the value specified. NOTE: If graded insulation is used, the manufacturer shall inform the purchaser. 4.3 Unless otherwise specified, pulse transformers shall be so constructed as to successfully pass the Moisture Resistance Tests of 8. 5. PEWOMANCE TESTS 5.1 Load Voltage Ratio and Polarity S
26、hall be measured by applying rated pulse voltage at the longest rated pulse length and appropri- ate pulse repetition frequency to one winding by means of a modulator capable of producing an approximately square pulse. All other windings shall be loaded with their rated loads. Voltage amplitude and
27、polarity of other windings shall be determined by applying the output of a suitable capacity or resistance divider to a calibrated synchroscope (synchronized oscilloscope) Polarities are determined by the connections to the synchroscope and voltages are measured on the pulse shape as viewed on the s
28、ynchroscope. 5.2 LoadTeat The pulse transformer shall be operated at rated power, pulse length and duty cycle with actual operating load or one which simulates it as closeIy as possible. The source or modulator shall simulate that for which the pulse transformer is designed as closely as possible. I
29、t shall be capable of meeting the requirements of 4.1 With test conditions as described in 7.1. 5.3 Pulse Shape Teat The acceptability of the pulse shape shall be determined by inspection of the output pulse, as viewed on a synchroscope while operating in the test circuit of 5.2. NOTE: The exciting
30、current, if used by the manufacturer as a measure of the amount of droop on top of an output voltage pulse, shall be determined by measuring the current through a non- inductive resistor in series with the winding to which is applied a pulse of the rated pulse voltage of the winding, at the maximum
31、rated pulse length, using the modulator described in 5.1 with all other windings open. The current as measured by calibrated synchroscope connected across the resistor shall not exceed a value determined by he maximum permissible droop in the output pulse specified in 3.1.6. The voltage drop across
32、the resistor used at the above exciting current shall not exceed 3% of the applied voltage. If the transformer design depends upon a reversal current to reset the flux in the core after each pulse, the following must be done before determining the exciting current as described above: Apply a d-c bia
33、s equal to the peak reversal current and having the same polarity through a suit- able choke, ta the winding in which the reversal current flows under operating conditions. 5.4 Dielectric Strength Teats A test potential, either d-c or a-c of commercial line frequency, shall be applied between each w
34、ind- ing and each other winding and between each winding and the core or case for one minute. All windings not under test shall be grounded to the core 6r case. The peak test voltage used between each pair of windings (or between each winding and the case) shall be four times the working non-induced
35、 voltage between the two windings or between the winding and the case for voltages up to 500 volts, two times the working voltage plus 1,000 volts for voltages between 500 and 2,000 volts, and one and a half times the working voltage plus 2,000 volts for voltages above 2,000 volts, In no case, excep
36、t between the two parts of a bifilar winding, shall a test voltage lower than 700 volts be used, A minimum test voltage of 160 VOES shall be used between the two parts of a bifilar winding, , /- f - 5.5 Induced Voltage Test Pulses of twice the rated pulse voltage and a minimum of the longest rated p
37、ulse duration shall be applied to the normal input winding. At least 26% of maximum PRF shall be used. The test potential shall be increased gradually (at the rate of approximately 2 KV per second) from zero to the specified value, maintained at this value for a period of one minute, and decreased g
38、radu- ally to zero. The pulses shall be supplied by a modulator of adequate power and suffickntly good regulation characteristics to limit the magnitude of spikes or droop to less than 10% of the pulse voltage. For transformers to be operated in circuits where the applied voltage may actually rise t
39、o twice normal during abnormal load conditions (See 3.1,7), the test voltage shall be raised to two and a quarter times the rated pulse voltage. NOTE: A load may be necessary when making this test. 5.6 Alternative Tests It is recognized that other tests may be used to determine certain characteristi
40、cs of a pulse trans- former. Use of such tests, and the test conditions, shall be subject to special agreement between purchaser and manufacturer. This provision may apply to tests such as turns-ratio, polarity, transmission characteristics, open circuit inductance, leakage inductance, capacitance,
41、losses, etc. 6. MARKING 6.1 Recommended Markings Are: 6.1.1 Manufacturers name or identification. 6.1.2 Manufacturers number. 6.1.3 Rated pulse durations, pulse repetition frequencies and maximum duty cycle. 6.1.4 Rated primary and secondary pulse voltages and pulse currents. 6.1.5 D-C resistance at
42、 26C. 6.1.6 Maximum filament voltage and curreilt in bifilar winding. 6.1.7 Diagram of windings with maximum allowable non-induced voltages. 6.1.8 Source and load impedance. 6.2 Each transformer shall be marked with at least 6.1.1 and 6.1.2. These markings shall be made, and all terminals shall be i
43、dentified, in a manner which is legible and permanent. 7. TEST METHODS 7.1 Load Test 7.1.7 The pulse transformer under test shall be mounted so as to be protected against drafts and shall not be subject to radiation from warmer objects. 7.1.2 The thermometer for measuring the ambient temperature sha
44、ll be protected against trivial temperature changes by means of an oil bath or other suitable thermal delay device. The load tests may be performed at room temperature. 7.1.3 The thermometer for measuring the temperature of the core or case shall be secured in con- tact with the core or case by mean
45、s of glaziers putty or other suitable material. 7.1.4 The pulse duration and pulse repetition rate for the test shall be determined by those which have the largest duty cycle. If the duty cycle is constant, the longest pulse duration operating condition shall be used. . 7.1.5 The load test specified
46、 in 5.2 shall continue until the temperature of the transformer case shows constancy for three successive readings at intervals of at least 30 minutes. 7.1.6 The temperature of the winding (for copper) shall be computed by the resistance method using the following formula (AIEE Rule 13-207). _ _ - _
47、- Y L , _ RS-17 E-PULSE VOLTAGE (IN VOLTS). U- RISE TIME (IN MICROSECONDS) b-OVERSHOOT (IN VOLTS) g-START OF FALL TIME C-OROOP (IN voLrs) t- PULSE OURATION (IN &FALL TIME (IN MICROSEGONOSI M IC ROSECONOS 1 8 - BACKSWING (IN VOLTS) f - RETURAI SWING (IN VOLTSI NOTE A: PULSE GURRENT- IF THE CURV OF Fi
48、GUUE I IS ASSUMED TO BE Of GORREFlt VS. rIME, THE PULSE CURRENT WOUCD BE REPRESENTED BY E. A SHELF MAY APPEAR ON THE LEADING DOE OF A CURRENT PULSE, BUT IT IS TO BE DISREGARDED IN THE MEASUREMENT OF RISE TIME. LEADING EDGE SHOULD BE EXTRA- POLATED TO TIME AXIS, AND RISE AS /N FIGURE 2. J t 0.1 TIME MEASURED STAUTING WITH O01 9 0.9 E
