ECA 180-1957 Power Transformers for Electronic Equipment《电子设备用电力变压器》.pdf

1、- EIA 180 57 3234b00 0028531 b / *- -. - - RETMA STAWDARD Power Transformers for Electronic Equipment RSm180 (Revision 01 TR-i02-B) April 1957 Engineering Department RADIO-ELECTRONICS-TELEVISIQN MANUFACTURERS ASSOCIATION , a. . Published by ELECTRONIC INDUSTRIES ASSOCIATION Engineering Department 20

2、01 Eye Street, N. W., Washington, D. C. 20006 Coprrl.bt 1967 bi R.dElcctionici-Tclevlion Manufieturcri Aunelntlnn All ?ish(. mcned PRICE $1.00 r- -. EIA 180 57 m 3234b00 0028533 T m RS- I 90 Page 1 POWER TRANSFORMERS FOR ELECTRONIC EQUIPMENT (From Standard TR-102-B and Standards Proposal No. 510 for

3、mulated under the cognzance of the RE TMA Engneering Committee SQ-4 on Transformers and inductora) e 1. SCOPE This specification covers iron core, power transformers up to 10 KVA for use in electronic equip ment where long life, reliability and continuity of operation is essential. 2. DEFINITIONS De

4、finitions of electrical terms used in this specification shall be in accordance with those given in “American Standard Definitions of Electrical Terms,” ASA No. C42-1941, except as otherwise noted. The “RMS working voltage” between any winding and any other winding or ground ahall be defined as 0.70

5、7 times the sum of the maximum d-c voltage and the peak a-c voltage which may appear between that winding and the other winding or ground under normal conditions of continuous operation. 3. PURCHASE SPECIFICATIONS The purchaser shall furnish information on the following subjects : NOTES: (1) Receive

6、r transformers are normally covered by RETMA Standards REC-119 and REC-120. (2) Transformers larger than 10KVA are covered by ASA (3-67.1. 3.1 Frequency or Frequency Range of Power Supply 3.2 Primary RMS Voltage or Voltages 3.2.1 Standard voltages are 115,230 and 460 volts. 3.2.2 See 6.1.2 (f) for n

7、ormal permissible overvoltage. Any more severe requirements shall be specified. 3.2.3 If taps are required, they shall be specified. Recommended taps are 106, 115, 126 or 210, 230, 260. 3.3 For Each Secondary Winding: 3.3.1 RMS load voltage and current (except for rectifier supply windings). (a) For

8、 each rectifier supply winding. 1. Type of rectifier and rectifier circuit. 2. DC current into the filter. 3. DC load voltage at the filter input or RMS load voltage of the winding. 4. Constants of at least the first section of the filter. 3.3.2 Center tap and D. C. current in center tap, if require

9、d. 3.3.3 RMS working voltages with respect to other windings and ground, 3.3.4 Electrostatic shielding, if required. 3.3.5 Regulation requirements, if any, including ehort circuit current limitations, in-rush cur- rents, exciting current, and surge voltage. NOTE: Standard current ratings are: 1.0, 1

10、.6, 2.6, 4.0, 6.3 amperes and decimal multiples of these values. NOTE: Whenever possible, DC voltages at the filter output should be chosen from the list of standard voltages iii 9. 3.4 Unusual Efficiency Requirements 3.5 Unusual Requirements as to External Magnetic Fields 3.6 Construction Features

11、: - - a- . - o _- EIA LBO 57 m 3234600 0028534 L m f RS- 180 Page 2 3.6.1 General assembly (for example: exposed core and coil, end bell, sheet metal encased, or hermetically sealed, dry or liquid filled). NOTE: In specifying construction, cognizance should be taken of requirements listed in 4.3 and

12、 4.4. 3.6.2 Terminals (for example : leads, screw studs or soldering lugs), 3.6.3 Mounting (for example: terminal end or opposite end). 3.6.4 Limiting dimensions. 3.7 Conditione of Operation: 3.7.1 Maximum ambient temperature for continuous operation. (a) Unless otherwise specified, the ambient temp

13、erature shall be assumed to be 60C. 3.7.2 Ambient temperature at which rated secondary voltage shall be delivered. 3.7.3 Maximum altitude if more than 5000 feet above sea level. 3.7.4 Duty cycle if not continuous. (Time on AND ratio of time on to time off.) 3.7.5 Where transformers are directly conn

14、ected to power lines, the additional requiremente imposing dielectric tests, induced voltage tests, and surge test shall be those required for thie class of transformers. 3.8 Other Specifications with which the Traneformer must comply (Army, Navy, Etc.) A PERFORMANCE STANDARDS 4.1 Permissible Temper

15、ature Rise When tested under standard conditions as described in 5.1, the maximum temperature riae of the transformer 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

16、purchaser and manufacturer, Class A insulation shall be used. 4.2 Secondary Voltagea When the transformer is operated as described in 6.2, each RMS secondary voltage, or d-c voltage at the filter input (correct to ambient temperature of 3.7.2) shall not differ more than three per cent from the speci

17、fied values. If any winding has a center tap, the RMS voltage across each half of that winding shall be between 49.5 per cent and 60.6 per cent of the voltage across the entire winding. 4.3 Moisture Resistance Unless otherwise specified, transformers shall be so constructed as to successfully pass t

18、he Moisture Resistance Tests of 7. 4.4 Corona Unless otherwise specified, magnitude of corona shall be within the limits tabulated in 8. 5. PERFORMANCE TESTS 5.1 LoadTest 5.1.1 Load Equipme and this constant temperature shall be the reference temperature (t). The observed resistance (R) shall be mea

19、sured as soon as practicable, and within 15 seconds after completion of the load test on units weighing less than 10 pounds. (i) The temperature rise of the transformer shall be computed by subtracting the temperature of the ambient air around the transformer at the end of the test from the temperat

20、ure of the hottest winding or of the core (whichever is higher) at the end of the test. 5.2 Secondary Voltage Test Immediately following the completion of the resistance measurements at the end of the load test and while the transformer is still hot and connected to the loads specified in 5.1.1, the

21、 sec- ondary voltages shall be measured with the transformer operating at rated line voltage and frequency. In correcting the measured load voltages to specified ambient temperature (section 4.2) it shall be assumed the temperature rises of the windings are the same as were computed in 5.1.2 (i). 5.

22、3 Dielectric Strength Test When the transformer has cooled to room temperature after completion of the secondary voltage test, it shall withstand without breakdown the application of alternating voltages of essentially sinusoidal wave shape and at a frequency of 60 cycles per second, as follows: 5.3

23、.1 A test potential of twice the RMS working voltage plus 1000 RMS volts shall be applied between each winding and each other winding and between each winding and the core or case. All windings not under test shall be grounded to the core or case. NOTE : Since the application of test potentials may

24、impair the insulation, any dielectric strength test shall, if repeated, be made at not more than 90 per cent of the specified test potential. 5.3.2 The test potentials shall be increased gradually, Le. at the rate of approximately 2 KV per second, from zero to the specified values, maintained at the

25、 specified values for a period of one minute, and decreased gradually to zero. After completion of the dielectric strength tests, the transformer shall withstand without break- down the application of test potential as follows : 5.4 Induced Voltage Test 7- -, - EIA LBO 57 m 3234600 0028536 5 m Page

26、4 5.4.1 The test potential shall be applied to any winding with all the other windings open-circuited. 3t.2 The test frequency shall be at least twice the minimum specified operating frequency. 5t.3 The test potential shall be of such magnitude that the voltage induced in the highest voltage winclin

27、g will be twice the load voltage specified for that winding. 5.4.1 The test potential shall be increased gradually from zero to the specified value, maintained at the specified value for a total of 7200 alternations and decreased gradually to zero. One eqd of the primary and each filament winding an

28、d the lowest potential terminal of all other windings shall be grounded during this test. 6. MARKING Each transformer shall be marked with at least the following information : 6.1 Manufacturers name or code numbers. 6.2 Manufacturers number. 7, MOISTURE RESISTANCE TESTS Tests shall be made according

29、 to thie Section when specified bu purchaser. 7.1 Following the Performance Tests in 6, the transformes shall be temperature conditioned by subjecting it to three consecutive temperature cycles, starting at room temporature, each cycle to consist of four steps of the following duration and temperatu

30、re : Step 1 2 3 4 - Table 1 Test Chamber Temp. 86 to 100 degrees C. 20 to 40 degrees C. -40 to -66 degrees C. 20 to 40 degrees C. 7.2 Humidity Run. After conditioning, the transformer shall be placed in a humidity chamber and shall be kept for 14 consecutive days in an atmosphere at a temperature of

31、 (66 f 3) degrees C. and at a relative humidity of (90 I 3) per cent. During this run all windings not connected to core 01 case shall be maintained at a positive potential of 76 to 125 volts d-c with respect to core or case. The humidity chamber shall be provided with suitable thermal insulation an

32、d with a means for keeping the air in continual circulation, to the end that the atmosphere surrounding the transformer under test shall meet at all times the specified temperature and humidity conditions. 7.3 Proof of Performance. On completion of the humidity run, the transformer shall be removed

33、rom 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 transformer shall then be given the following tests, in the order stated, and without delay between tests: 7.3.1 It shall withstand, without b

34、reakdown, the Dielectric Strength Test given in 6.3, except that the test potential shall be 600 RMS volts or 126 per cent of the RMS working voltage, which- ever is greater. 7.3.2 It shall withstand, without breakdown, the Induced Voltage Test of 6.4, except that the test potential shall be 126 per

35、 cent of the RMS working voltage. 7.3.3 It shall be given the Load Test of 6.1, starting within 16 minutes after completion of the induced voltage test and continuing for at least 6 hours and until the temperature of the core or case sho.ws constancy for three successive readings at intervals of at

36、least 30 minutes. During this run the transformer shall be inspected frequently and any evidence of distress (such as cracking, deformation, leakage of compound, or evolution of steam or smoke) shall constitute a failure. 7.3.4 The Secondary Voltage Test described in 6.2 shall be repeated and the vo

37、ltages shall not differ by more than two per cent from the values observed in the initial Secondary Voltage Test. - - - Time 46 minutes 30 minutes 46 minutes 30 minutes I EIA LBO 57 3234600 0028537 7 T- -t. RS-180 Page 5 8. CORONA I EXPLANATORY t It is an established fact that corona has a detriment

38、al effect on insulation and, when present in sufficient magnitude, will cause insulation failure. In general, the equipment manufacturer and the user share in the responsibility foi. the presence and the magnitude of corona: the manufacturer in the need for his designing the equipment to minimize th

39、e presence of corona and the user in the need for his maintahing the equipment dry and clean to this same purpose. . Both the presence and magnitude of corona are influenced by humidity and temperature and are otherwise unstable. The measurement of corona serves, therefore, more to provide an indica

40、tion of level than of an exact value. I 8.1 The Measurement of Corona 8.1.1 Measurements shall be made only on clean dry transformers. 8.1.2 Measurements shall be made using the method and noise meter described in RMA Engi- neering Bulletin No. 32 titled “Methods of Measuring Radio Noise, 1940” and

41、using the circuit of Figure 3, thereof. 8.1.3 A test potential of 106% of RMS Working Voltage (a) Shall, where practicable, be applied between the winding under test and the core or case with winding terminals shorted or ; (b) Shall, where (a) is impracticable, be induced in the winding under test;

42、while in either case, other windings and core are grounded. (a) On first measurement be less than the following limiting values 8.1.4 The magnitude of the corona level across insulation subject to damage by corona shall RMS Working Voltage (Kilovolts) Up to 8.6 kv 8.61 to 15 kv Corona Level (Microvo

43、lts) 1,000 p volts 2,600 p volts (b) On second or repeated measurement, be less than twice the above stated limiting values. 9. STANDARD DC SUPPLY VQLTAGES AT THE FILTER QUTPUT ARE AS FOLLOWS: DC Supply Voltage 100 300 750 2000 150 400 1000 2600 180 600 1250 3000 200 600 1600 4000 260 NOTE: The above values are used directly for unregulated supplies. For regulated supplies, it is recommended that the unregulated voltage be one value higher than the output voltage required. (Le. Use transformer normally employed to provide 180 volts DC for supplying regulated 160 volts DC.)