1、RETMA STANDARD Iron Core Chargng Inductors RS-181 (Revision of TR-127) I March 1957 Engineering Department RADIO-ELECTRONICS-TELEVISION MANUFACTURERS ASSOCIATION r 1 EIA LBL 57 3234600 0028539 O 4 NOTICE RETMA standards are adopted in the public interest and are designed to eliminate misunder- stand
2、ings 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-member of RETMA from manufacturing or selling products not
3、 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, the Association does not assume any liability to any pat
4、ent owner, nor does it assume any obligation whatever to parties adopting the recommended standards or practices. Published by ELECTRONIC INDUSTRIES ASSOCIATION Engineering Department 2001 Eye Street, NOW., Washington, D. C. 20006 Electronic Industries Association 1971 All rights reserved .Price $2.
5、20 Printed In U.RA. EIA 181 57 m 3234h00 0028540 7 m RS-I81 Page 1 IRON CORE CHARGING INDUCTORS (From Standard TR-127 and Stamlards Proposal No. 514 formulated utzder the cognizance of RETMA ErvginserZng Committee SQ-4 on Trarcsf owners and Inductors) 1. SCOPE This standard covers iron core charging
6、 reactors for use in radar transmitters and similar equip- ment where long life, reliability and continuity of operation is essentiai. 2. DEFINITIONS Definitions of electrical terms used in this standard shall be in accordance with those given in “American Standard Definitions of Electrical Terms”-A
7、SA Standard C42-1941. Definitions of electrical terms used in this standard, but not covered by ASA Standard C42-1941, are given below: 2.1 Charging Inductor A charging inductor is an inductor placed in the charging circuit of a pulse forming network. Because of the oscillatory nature of the chargin
8、g, network capacitance ia charged to almost double the power supply voltage, at which time the switch shunting the network conducts, discharges the network and develops a pulse across the load of the modulator. 2.2 Pulse Repetition Frequency (PRF) Pulse repetition frequency (PRF) ia the number of ti
9、mes per second the pulse is transmitted. 2.3 Resonant Frequency of Charging (fB) Resonant frequency of charging reactor inductance and network capacity as determined by 2.4 Resonant Charging Resonant charging occurs when the switch starts to conduct at the peak of the sine wave of voltage across the
10、 network. fa should approximately equal - PRF for this condition. In linear charging, the switch starta to conduct while the voltage across the network condenser is still rising. fR should be leas than - PRF for this condition. 2 2.5 Linear Charging 2 2.6 Resonant Charging with a Charging Diode A di
11、ode is placed in series with the charging inductor with its plate connected to the high voltage side of the inductor and its cathode connected to the wmmon junction of the switch and the pulse forming network. The network charges to full voltage, remains there until the switch conducts, and permits
12、operation at PRFs less than Zf,. 2.7 Graded Insulation 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 low potential end. It is applicable to charging inductors where one end is permanently connected
13、to a fixed potential while the other end may swing to essentialy double this Axed potential. 2.8 RMS Working Voltage The “RMS working voltage” between the winding and ground shall be defined as 0.707 times the sum of the maximum d-c voltage and the peak a-c voltage which may appear between the wind-
14、 ing and ground under normal conditions of continuous operation. 2.9 Average Current (kc) This is the current drawn from the power supply over one or more complete cycles. EIA 181 57 3234600 0028541 9 RS-18 1 Page 2 3. PURCHASE SPECIFICATIONS The purchaser will specify 3.1 Electrical Features 3.1.1
15、The rated value of inductance at approximately 25C. (a) Permissible variation of inductance over frequency, voltage and current range of the appli- cation, as specified in 3.1.2, 3.1.3, and 3.1.4. NOTE: If no variation in ide is specified, the inductance measured at $42 Ide shall not differ from the
16、 inductance measured at Idc by more than 20 percent. (b) Taps and tap tolerance. 3.1.2 Type of charging desired (resonant, linear, or resonant with a charging diode) and the pulse repetition frequency or frequencies. 3.1.3 Peak, RMS and average current for each frequency specified in 3.1.2. 3.1.4 Ma
17、ximum operating voltage at all terminals. 3.1.5 The modulator circuit diagram, complete with component values and, operating conditions including losses, may be given instead of the voltages and currents in 3.1.3 and 3.1.4. 3.2 Construction Features 3.2.1 General Assembly: (For example: non-encased
18、core and coils, end bell, sheet metal enclosed, dry or liquid filled, or hermetically sealed). NOTE : In specifying construction, cognizance should be taken of requirements imposed by 3.1.4, 3.3.2, 3.3.4, 3.4, 4.3, and 4.4. 3.2.2 Terminals, (For example : leads, screw studs or soldering lugs). 3.2.3
19、 Mounting, (For example : terminal end or opposite end). 3.2.4 Limiting dimensions and weight. 3.3 Conditions of Operation 3.3.1 Maximum ambient temperature for continuous operation. 3.3.2 Maximum altitude if more than 6000 feet above sea level. 3.3.3 Unusual requirement or operating conditions such
20、 as intermittent operation. 3.3.4 Special conditions, such as ability to withstand vibration. (a) Unless otherwise specified, the ambient temperature shall be assumed to be 60C. 3.4 Other specifications with which the inductor must comply (Army, Navy, etc.). 4. PERFORMANCE STANDARDS 4.1 When tested
21、under standard conditions as described in 7.1, the maximum temperature rise of the inductor winding shall not exceed the limit for 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
22、, class A insulation shall be used. 4.2 Winding Voltage. The winding shall be insulated so as to withstand the DC voltage at one terminal, twice the DC voltage at the other, and an AC voltage across the winding of peak value equal to the DC voltage. The high voltage end of the inductor winding shall
23、 be designed to with- stand the voltage produced in actual operation as specified in 3.1. 4.3 Unless otherwise specified, inductors shall be so constructed as to successfully pass the Mois- ture Resistance Tests of 8. 4.4 Unless otherwise specified, Magnitude of Corona shall be within the limits tab
24、ulated in 9. - r. EIA 181 57 3234600 0028542 O E RS-181 Page 3 5. PERFORMANCE TESTS e 9.1 Indiictance Tekt The inductance shall be measured in a suitable circuit, with the greatest value of average current, the maximum voltage, and the corresponding frequency fn specified in 3.1. If desired, a highe
25、r or lower frequency than fB, with voltage increased or decreased in proportion, may be used, provided that proper allowances are made for inductance variatioiis with frequency. NOTE: There will be some difference between a reading thus made and the inductance value which would be read at the resona
26、nt frequency, depending on the change in magnetic permeability between the two frequencies. Provision for this correction must be made by the manufacturer. A second measurement, made with the lowest Iae specified and with the same alternating voltage, shall show an inductance within the variation sp
27、ecified in 3.1.1. 5.2 Alternate Teat In lieu of the inductance test of 5.1, the characteristics of the inductor may be determined by operating it in the modulator circuit for which it is designed. 5.3 Load Test The load test shall be performed in accordance with 7.1. The inductor, at room temperatur
28、e, shall withstand without breakdown, the application of alter- nating voltage of essentially sinusoidal wave shape and at a frequency of 60 cycles per second as follows : 5.4.1 A test potential of twice the “RMS working voltage of the lowest voltage terminal plus 1000 RMS volts shall be applied bet
29、ween the winding and the core or case, with the terminals short circuited together. NOTE: Since the application of test potential may impair the insulation, any dielectric strength test shall, if repeated, be made at not more than 90% of the specified test potential. 5.4.2 The test potential shall b
30、e increased at a rate of approximately 2 KV per second from zero to the specified value, maintained at the specified value for a period of one minute and decreased at the same rate to zero. NOTE: If the insulation in the charging choke is uniform, and if the terminals are the same size, then a test
31、potential of twice the “RMS working voltage of the highest voltage terminal plus 1000 RMS volts shall be applied as in 6.4.1. 5.4 Dielectric Strength Test 5.5 Induced Voltage Teat The inductor shall withstand without breakdown, the application of test potentials as follows : 5.5.1 An essentially sin
32、usoidal voltage of a frequency equal to or greater than the rated plus repetition frequency and with an RMS value equal to=+ 1000 RMS volts shall be applied 5.5.2 This test potential shall be increased at a rate of approximately 2 KV per second-from zero to the specified value, maintained at the spe
33、cified value for 15 seconds and decreased at the same rate to zero. NOTE: If the insulation level of the various terminals is different (graded insulation) a surge or other voltage test which will stress the highest voltage terminal to2 (peak voltage of highest voltage terminals) + 1000 RMS volts, m
34、ust be applied to the winding with all taps open. This may be done by connecting a transformer secondary of the proper peak voltage rating to the lowest voltage terminal of the charging choke and applying the induced voltage test of 5.5.1 to the charging choke winding, taking precautions to insulate
35、 the test voltage source by the proper amount. across the winding with all taps open circuited. v2 v2 In those charging chokes in which all terminals are of the same insulation level, and which ace tested at a test voltage determined by the rating of the highest voltage terminal, the foregoing surge
36、 test for the high voltage terminal will not be necessary. - 7- /, ;I EIA 181 57 m 3234600 0028543 2 m r i RS-181 Page 4 , 6. MARKING 6.1 Recommended Markings Are: 6.1.1 Manufacturers name or identification. 6.1.2 Manufacturers number. 6.13 Inductance. 6.1.4 Rated direct current. 6.1.5 Maximum volta
37、ge at each side of reactor. 6.1.6 D-C resistance at 26C. 6.1.7 Minimum and maximum PRF. 6.1.8 Terminal identification. 6.2 Each inductor shall be marked with at least 6.1.1, 6.1.2, and 6.1.8 in a Fanner which is per- manent and legible. 7. LOAD TEST 7.1 Test Methods 7.1.1 The inductor under test sha
38、ll 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 shall be protected against trivial temperature changes by means of an di1 bath or other suitable thermal delay device. The load te
39、sta may be performed at room temperature. 7.1.3 The thermometer for measuring the temperature of the core or case ahall be secured in contact with the core or case by means of glaziers putty or other suitable material. 7.1.4 The inductor shall be operated in its modulator circuit (real or simulated)
40、 under the set of conditions specified in 3.1 which produces maximum loss. 7.1.5 The load test shall continue until the temperature of the inductor core or 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
41、be computed by the resistance method using the following formula (A.I.E.E. Rule 13-207) : R r T = - (234.6 + t) -234.6. t = reference temperature in “C of winding. T = temperature in “C of winding to be calculated. r = resistance in ohms at reference temperature t. R = observed resistance in ohms at
42、 temperature T. In applying this method, the resistance (r) at reference temperature (t) shall be measured after conditioning the inductor for at least eight hours in a location free from drafts and until three consecutive temperature readings of the ambient and core or case taken at 30-minute inter
43、vals are constant; and this constant temperature shall be the reference temperature (t) . The observed resistance (R) shall be measured within one minute after completion of the test run. 7.1.7 The temperature rise of the inductor shall be computed by subtracting the temperature of the ambient air a
44、round the inductor at the end of the test from the temperature of the winding or of the core (whichever is higher) at the end of the test. The observed resistance (R) shall be measured within nk-minute after completion of the test run. 8. MOISTURE RESISTANCE TESTS Tests shall be made according to th
45、is Section when specified by purchaser. - EIA LB1 57 3234600 0028544 4 = RS-181 Page 5 8.1 Following the Performance Tests in 5, the inductor shall be temperature-conditioned by sub- jecting it to three consecutive temperature cycles, starting at room temperature, each cycle to con- sist of four ste
46、ps of the following duration and temperature: 0 Table I Step Test Chamber Temp. - 1 85 to 100 degrees C. 2 20 to 40 degrees C. 3 -40 to -66 degrees C. 4 20 to 40 degrees C. Time 46 minutes 30 minutes 45 minutes 30 minutes - 8.2 Humidity Run After conditioning, the inductor shall be placed in a humid
47、ity chamber and shall be kept for 14 consecutive days in an atmosphere at a temperature of (66 f 3) degrees C, and at a relative humidity of (90 f 3) percent. During this run, all windings not connected to core or case shall be maintained at a positive potential of 76 to 126 volts d-c with respect t
48、o core or case. The humidity chamber shall be provided with suitable thermal insulation and with a means for keep- ing the air in continual circulation, to the end that the atmosphere surrounding the inductor under test shall meet at all times the specified temperature and humidity conditions. 8.3 P
49、roof of Performance On completion of the humidity run, the inductor shall be removed from the chamber and allowed to stand in air at room temperature for 16 minutes, during which period any surface moisture may be removed with a dry cloth. The inductor shall then be given the following test, in the order stated, and without delay between tests : 8,3.1 It shall withstand, without breakdown, the Dielectric Strength Test given in 6.4 except that the test .potential shall be 600 RMS volts or 126 percent of the RMS working voltage, which- ever is greater. * 8.3.2 It shall
