1、SAE ARP*L5A 7b 8357340 002b230 T = - 3s- f9 I ARP 159A PRACTICE Revised 1-15-76 AEROSPACE RECOMMENDED Society of Automotive Engineers, Inc. 400 COMMONWEALTH DRIVE, WARRENDALE. PA 15096 DIELECTRIC TESTING OF SPM PLUGS . PURPOSE This report provides information on instrmentation and procedure for the
2、dielectric testing of aircraft piston engine spark plugs to determine their functional condition. SC0.PE This report describes a method of determining the dielectric integrity of a spark plug by subjecting the insulation in the plug voltage stress, 1. 1.1 1.2 2. 2.1 2.2 MJXODUCTION This test is cons
3、idered applicable where more comprehensive information about the condition of the spark plug is desired. It may be used by manufacturers and testing facilities to determine functional integrity of new or used spark plugs. A spark plug contains a high voltage insulator used in a special application.
4、From an electrical standpoint, successful operation is dependent upon its ability to withstand high voltage impressed on it. in general, so far as testing is concerned, sparking between the electrodes is incidental. If the insulator in the spark plug will withstand the electrical strain imposed by s
5、ubjecting it to high voltage, a spark can occur between the electrodes in the presence of engine operating pressures when the gaps are within the limits of O. O10 in. (O. 25 mm) to O. 030 in. (O. 75 mm). DE,SCRIPTION OF EQUIPMENT Basically, the test equipment consists of a pneumatic or bnmersive-typ
6、e device that will prevent sparking across the air gap while subjecting the spark plug insulator to an electrical stress from a voltage source. Included in the electrical device is a means of detecting electrical faults in the spark plug. Quenching of the air gap may be accomplished by alternate mea
7、ns. One is by positioning the spark plug in a dielectric fluid such that gap and approximately O. 250 in. (6 mm) of insulator adjacent to the air gap is immersed. . Another means consists of a pressure chamber into which the spark plug is inserted for test. control valve, pressure gauges and a sourc
8、e of dry compressed gas (air, carbon dioxide or nitrogen). Figure 1 illustrates a schematic for such a device. This chamber is equipped with a pressure regulator, In conjunction with the spark quenching device described in 2.1 is an electrical device as illustrated in Fig. 2, consisting of a high vo
9、ltage transformer, voltage control, meter, in- dicating lights and controls to electrically stress the spark plug insulator and, at the same time, indicate any electrical leakage or breakdown of the spark plug insulator. A voltage con- trol and voltmeter are provided to permit adjustment of the inpu
10、t voltage. Operation is from 110 volt, 60 hertz true sinusoidal voltage. . - . . ., -.= I L . . Copyright 1976 by Society of Automotive Engineers, Inc. All rights reserved. - Printed in U.S.A. - - - SAE ARP*LSA 7b m 8357340 002b231 1 m ARP 159A I -2 - 3. TEST PREPARATION 3.1 Before testing, spark pl
11、ugs should be prepared as follows: a, Remove oil and grease. b. Dry thoroughly in oven at 250OF (120%) to 350F (180OC) for not less than 4 hours. 4. TEST PROCEDURE 4.1 The recommended test voltage applied to the spark plug is 9000 volts (RIMS) obtained by adjusting the primary voltage control. The m
12、eter should read approximately 98 volts for 9000 volts (RMS) output using the 110 to 10,000 volt transformer. A calibration check of the transformer output should be made for proper operating potential. 4.2 Install the spark plug in the test fixture and connect the appropriate spark plug lead. Press
13、urize the cbamber to approximately 450 psi-(3.1 Ma). 4.3 To energize the electrical system, press the test switch (sw 1). indicator light (PL) will indicate that power is being supplied to the auto-transformer. The test switch should be held down for one minute. If, during this period, the output ne
14、on lamp (NE) does not glow, the spark-plug is considered good. If the output neon lamp (NE) does glow, the spark plug is faulty or shorted internally. A steady glow indicates flashover in the barrel or a break in insulator; The following precautionary measures should be taken: - 4.4 . a. To be certa
15、in that the “output“ neon lamp is functioning properly, a satisfactory check can be made by grounding the spark plug lead with the system inoperative. Energize the system and increase the primary voltage (as shown on the voltmeter) to a point where llglowingli of the neon lamp begins. Complete but n
16、ot intense lighting should occur between 50 and 55 volts. If a higher voltage is required, the neon bulb should be replaced or any other malfunction should be corrected. b. The adjustable auto-transformer should be examined occasionally for excessive wear on the winding which may be caused by a worn
17、 brush. Blackened or corroded contact surfaces should be cleaned with crocus cloth or very fine sand paper to insure proper contact. Loose particles should be removed from the windings with low pressure air stream. PREPARED BY SAE COMMITTEE E-30, IGNITION RESEARCH 1 _. 7 SAE ARP*L57A 76 83573LiO O02
18、6232 3 I -3- I_ PRESSURE GAUGE DRY COMPRESSED GAS SUPPLY 6 PRESSURE CONTROL REGULATOR VALVE TEST CHAMBER FIGURE 1 SPARK PLUG QUENCHING DEVICE (PNEUMATIC METHOD) CW-1 - Momentary Operation Test Switch T-1 - Primary Voltage Control (3 ampere variable auto- trans former T-2 - Transformer, 110 V.A.C. 60 Hz to 10,000 V. 10 m.a (Similar to oil burner transformer) P.L. - Indicator light V - Voltmeter, 0-150 V.A.C. Cl - Capacitor, .O01 mfd., 20 KV C2 - Capacitor, .O02 mfd., 600 V Ri - Resistor, 10 K ohms, 1/2 Watt N.E. - Neon lamp (NE48) FIGURE 2 ELECTRICAL TEST CIRCUIT
