1、Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,- io one or mor; other circuits at the same frequency usually with-changed values of voltage and current. 3.3.3 Dr t e transformer. A dry type transformer is a transformer cooled by the natural circdt2Eo
2、f air and not liquid-immersed. 3.3.4 Primary winding, 3.3.5 Cecondarx winding. 3.3.6 -e (in a transformer). The primary winding is the winding on the input side. . The secondary winding is the winding on the output side. A tap in a transformer is a connection brought out of a winding at some pTnF be
3、tween its extremities, usually to permit changing the voltage ratio. 3.3.7 Rated kilovoltam ere of a transformer. The rated kilovoltampere (kVA) of a trans- former is thermt which can be3eTivered for the time specified at approximately rated secondary voltage- and rated frequency without exceeding t
4、h; specif ied tmperature iimitations. 3.3.8 Ratio of fi transformer. The ratio of a transformer is the turn ratio of the transformer. - # 3.3.9 No-load losses of a transformer (excitation losses of a transformer), The no-load losses of a -rareTho losses in a transformer that-jlsxcited at rated volta
5、ge and frequency but not supplying load. NOTE: No-load losses include core loss, dielectric loss, and copper loss in the winding due to exciting current. # 3.3.10 Load losses of 5 transformer (im edance losses of a transformer). The load losses of a transformera= those losses ikotransformerhzhare in
6、cident to the carrying of load. NOTE: Load losses include I R loss in the windings due to load current, stray loss due to 2 stray fluxes in the windings, core clamps, and so forth, and to circulating currents, if any, in parallel windings. 3.3.11 Total losses of a transformer. The total losses of a
7、transformer are the losses represented bm Zeno-load losses and the load losses. 3.3.12 Re ulation of a transformer. The regulation of a transformer is the change in secondary voltaie, exprezed in percent of rated secondary voltage, which occurs when rated kVA output at a specified power factor (pf)
8、is reduced from rated value to zero, with the primary impressed terminal voltage maintained constant. the voltage rhodace Fated current through a winding of the transformer when another winding is short circuited, with the respective windings connected for rated voltage operation, and is expressed i
9、n percent of the rated voltage of the winding in which the voltage is measured. 3.3.14 Excitin current of 5 current. The exciting current of a transformer is the current whichdn-nang um excite the transformer when ali other windings are open-circuited, and is expressed in percent of the rated curren
10、t of the winding in which it i8 measured. designation omewe?nZtantaneous directions of currents in its leads. secondary leads are said to have the same polarity when at a given instant the current enters the primary lead in question and leaves the secondary lead in question in the same direction as
11、though the two leads formed a continuous circuit. The lead polarity of a single-phase distribution or power transformer may be either additive or subtractive. adjacent leads from the windings in question is connected together and voltage applied to one of tho windings: (a) The lead polarity is addit
12、ive if the voltage across the other two leads of the windings in question is greater than that of the higher voltage winding alone. (b) The lead polarity is subtractive if the voltage across the other two leads of the windings in question is less than that of the higher voltage winding alone. 3.3.13
13、 Im edance volta e of a transformer, The impedance voltage of a transformer is 3.3.15 Lead olarit of a transformer, The lead polarity of a transformer is a Primary and If one pair of 2 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-3 Provided by IHS
14、Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-T-1722lB (SHIPS) s 3.10 Characteristics, Characteristics of the transformers shall be as shown in table II* II Table II - 15OOC rise transformers. # II I I I baximum losses keauiation maximu5; 3.5 3.5 3.; i i 5 5
15、3.5 I5 15 570 1300 1460 950 YValues for inrush current are applicable to transformers with 450-volt primary. YTransformer to be submitted from each division for qualification (soe 4.3.1) ZSpacers used to attain the “F“ and “G“ dimensions specified in table III. ARegulation impedance and total losses
16、 shall he given at 15OOC. usee 4,3,1, resistance- primary and secondary windings for transformers of the same size and design shall he not more than minus 5 percent, more than minus 10 percent. sonnel. The transformers shall conform to the safety requirements of MIL-E-917. that: plus orus 1 percent
17、from the ratio of rated voltages indicated on the idetifi- cation plate. For transformers of other voltages maximum inrush current shall be the same percentage of the pzimary load Currents. 3.11 Windina resistance. On a.percentage basis, the average of the variations in The resistance of any one win
18、ding shall vary not 3.12 Safetx. 3.13 Ratio. Transformers shall he so designed that the turn ratio shall not vary more The transformers shall be designed for the utmost safety of ships per- 3.14 Polaritx. Transformers shall be of additive polarity. 3.15 O oratin noise. Transformers shall be designed
19、 to meet the noise level require- ments speciM.i;ra;. 3.16 ShockproonecE;. Transformers shall be designed to withstand high impact shock without mechanical damage or failure of parts as specified in MIL-S-901 for grade A, class I, type A (see 4.6.10). 3.17 Short circuit, Transformers shall be design
20、ed to withstand short circuit currents as specifieUin4.b.13. 3.18 Wei ht. Transformers complete with case and including wiring and mounting pro- 3.19 Volume, Transformers shall be SO designed and constructed that: the volume does The maximum overall dimension.in vision shal9 4.6.8 Weight and X - - X
21、 3.18 and 3.19 4.6.9 volume Shock X - - I 3.16 4.6.10 Post shock X I - - 3.16 4.6.10.3 Dielectric X I X - 3.20 4.6.11 Inrush current X X - - 3.10 4.6.12 Short circuit I X I XI-1- 13.17 r 4.6.13 - - Noise X X 3.15 4.6.14 I 4.4 Qualit conformance ins ection. At 3 year intervals after qualification ins
22、pection a traneford rating shail*ed from the applicable qualification division and subjected to the quality conformance, group A tests shown in table VI. This requirement is based on quantity production. quality conformance group A test before the manufacturer will again supply a transformer rating
23、in the particular qualification division, the tests shall be conducted on an appli- cable transformer of the subsequent contract or order. Each production line transformer shall he subjected to all the tests shown in table VI in the quality conformance, group B tests. In addition, production line tr
24、ansfomers shall also be subjected to the quality conformance group C tests on the selection basis shown in table VII. If it appears that more than 3 years will elapse-from the last Table VI1 - Sampling for quality conformance, group c tests. Number of transformers Minimum numbid d-voltacle outlet le
25、ads shall be connected together. applied to the high-voltage winding. Readings of the applied voltage and voltage between the right-hand adjacent high-voltage and lowvoltage leads shall be observed. voltage reading is less than the former (indicating the approximate difference in voltage between tha
26、t of the high-voltage and low-voltage windings) the polarity is subtractive, the latter is greater than the former, the polarity is additive. Any convenient vlue of alternating voltage not exceeding rated voltage shall be If the latter If 10 Provided by IHSNot for ResaleNo reproduction or networking
27、 permitted without license from IHS-,-,-MIL-T-17221B b1 9777706 0087179 T MI L-T- 17 2 2 1B (SHIPS ) 4.6,Z.Z Polarity % standard transformer. A standard transformer of known polarity and having the same ratio as the transformer to be tested may be used. windings of both transforwers shall be connect
28、ed in parallel. The left-hand side law-voltaae The high-voltage leads (facing the low-voltage side) of both transformers shall be connected together. The- right-hand side leads shall be left free. voltage to the high-voltage windings and measure the voltage between the two free leads. A zero or negl
29、igible reading of the voltmeter will indicate that the relative polarities of both transformers are identical. with these connections apply a reduced value of 4.6.3 Ratio. The turn ratio between the primary and the secondary windings shall be accurately determined by either of the methods specified
30、in 4.6.3.1 through 4.6.3.2.2. 4.6.3.1 Voltreter method. The ratio test shall be made with rated or lower voltage at rated or higher frequencyied to either the high or low voltage leads of the transformer. Simultaneous readings of a voltmeter in the high-voltage winding and a voltmeter in the low- vo
31、ltage wining shall be taken and recorded. set of readings obtained, the average of these two sets of readings shall be used in checking the ratio. The meters shall be interchanged and another 4.6.3.2 Standard transformer method. The transformer to be tested shall be connected in parallel with a stan
32、dard transfomf the same nominal ratio. The secondaries shall also be connected in parallel but with a voltmeter or detector in the connection between two terminals of similar polarity and so arranged as to read the difference between the two secondary voltages. If the manufacturer desires, the volta
33、ges in each secondary winding may be obtained. Where this method is used, however, the voltmeters shall be interchanged and a second set of readings shall be obtained. The average of the results shall be used in determining the ratio. are shown on figures 4 and 5. and design shall be within plus or
34、minus 1/2 of 1 percent of turns ratio shown on applicable 4.6.3.2.1 The connections for the ratio test by comparison with standard transformer 4.6.3.2.2 The variation of the value of ratio between transformers of the same size, drawing. 4.6.4 Impedance. Either the primary or the secondary winding sh
35、all be short circuited and voltage at rated frequencv applied to the other windinq and adjusted to circulate rated current in the winding. -Wit!i-cu;ent and frequency adjusted to rated values, simultaneous. readings shall be taken on the ammeter, voltmeter, wattmeter and frequency meter. The actual
36、design value appears on the drawings. The impedance values for transformers of the same size, and design may vary from the value shown on the drawings by not more than plus or minus 7-1/2 percent. 4.6.5 Losses. 4.6.5.1 No-load losSeS. The no-load losses shall be accurately determined. Rated voltage
37、shall be appliedeither the primary or secondary windings. The frequency shall.be 400 112. Simultaneous readings shall be nade of frequency, voltage, watts (low power factor wattmeter), and amperes. The actual design value appears on the drawings. The no-load lo.ss for transformers of the same size,
38、esign, and type may exceed the value shown on the drawing. by 10 percent; however, in no case shall the no-load losses exceed the maximum allowable no-. load losses shown in table II. . 4.6.5.2 Total losses. From the data obtained in the impedance test and no-load loss test, the totamsesshall be det
39、ermined. The total loss for transformers of the same size, and design may exceed the value for full load loss watts shown on the drawing by 6 percent, but in no case shall the value exceed, the value for full load losses shown in table II. The actual design value appears on the drawings. 4.6.6 Excit
40、ing current. The exciting current shall be determined during the no-load loss test, and shall meed the maximum allowable value of exciting current shown in table II. . O 11 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-T-17221B (HIPS) based on
41、tlie*Galues of impedance volts and impedance watts, corrected to 150C. Either of the folloviing formulae may be used in the calculation of the regulation: 4.6.7 Re ulation The regulation of a transformer shall be determined by calculation Formula I: Regulation = pr + qx + (PX 2 qr) (a) Ivhen the loa
42、d is lagging 2 (b) When the load is leading 2 (PX + qr) 2 Regualtion = pr - qx + Iormula 118 Regulation = a - 1/2a2 + l/2a3 - 5/8a4 + 7/8a Where : 5 p = Cos 8 = power factor of load. e = phase angle of load current, positivo for leading current, negative for fi = impedance angle of transformer, r =
43、resistance factor = q=+ .li-p2. lagging current. im edance loss in kw. P rated kva z = impedance factor = -+ x = reactance factor = + W a = 2 COS ( + e) + +* 2 The quantities of regualtion are on a per unit basis so that the result must be multiplied by 100 to get: the regulation in percent. 4.6.8 I
44、leating. 4.6.8.1 General. Ileating tests on transformers shall be made under conditions equiva- lent to normal operating conditions, that is, rated voltage, rated frequency, rated current, and the duty specified. shall be as specified in 4.6.8.2 through 4.6.8.5.3. assembled trand constant temperatur
45、es havebeen attained in all parts of the transformer. Tho test methods to be employed and the precautions to be observed 4.6.8.2 Accembl transformer, The heating test shall be made only on the completely 4.6.0.3 Duration of test. The heating test for transformer shall be continued until 4.6.0.4 Meth
46、od of loading. The following methods of loading transformers for the heating test amezar (a) The transformer may be loaded directly, That is, with rated voltage applied to the primary and sufficient load on the secondary to load the transformer to rated kVA capacity. (b) Duplicate single-phase trans
47、formere may be tested in banks of two by connecting both the high-voltage and low-voltage windings in parallel and by applying rated excitation voltage at rated frequency to one set of paralleled windings, as shown on figure 6. The connections of the other pair of windings shall be opened at one poi
48、nt and a voltage impressed across the break just suf- ficient to circulate rated currents through the windings, The circulated current should preferably be at rated frequency. Note: If other than rated frequency is applied to the opened windings the value of the current should be adjusted to yield t
49、he true impedance watts of the transformer, 12 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-HIL-T-17221D (SIIIIS) 4.6.8.5 Measurement of the anhient temperature. Unless otherwise snecif ied in the con- tract or order, transformers may be tested at any convenient room temperature above 10C. With a minimum distance of 2 inches between units, the maximum permissible temperature rises spec
