Jennings PV Family Capacitor
Reaches High Ratings under All Testing Conditions

The PV Family of high current capacitors is one of the latest innovations to emerge from Jennings Technology and sets a new standard for vacuum variable capacitors. This product was designed to endure a rugged high current environment. To obtain the specifications and quality data Jennings quality and engineering group put the PV family of capacitors through many rigorous testing procedures. Five of each type of capacitor went through six different testing procedures and the test results proved to be consistent.

Type of Test: Mechanical Life

Procedure:
Each unit was placed in a horizontal position with the variable end facing the stepper motor. A custom fixture ensures secure mounting. To avoid any side loading, a flex coupler was used from the lead screw to the motor. The unit rotated 5 turns clockwise from about 750 pF to approximately 250 pF and back, traveling 50% of the capacitance range. The motor speed was set at 500 rpm. Each unit was stopped every 250,000 cycles to check the internal withstand voltage at its rated value of 5 kVp, and to measure the torque versus turns in both directions.

Equipment Used:

  • PC Rotation Controller
  • Slo-Syn Synchronous/Stepping Motor
  • Hewlett Packard 4273A 1 kHz Preset C Meter
  • Sturtevant-Richmont Torque Gauge
  • Jennings Technology High Voltage Tester
  • Jennings Technology barnacle detector

Result:

The units reached over 2,500,000 cycles while achieving all original specifications. Some units are still under test and are currently running with approximately 3,816,750 cycles.

Pv 4-500 Beta 4#4 Equivalent Parameters 11/29/2000

Capacitance (pF)

EQVR (microOhm)

EQVL (nH)
EQVC (pF)
Resonant Frequency (MHz)
80 28.2125 35.2019 80.0669 94.550
90 21.6869 34.0974 89.6097 90.8425
100 31.0799 33.3249 101.310 86.1400
150 19.7981 34.7351 147.601 70.0525
200 22.8328 34.0123 203.310 59.9050
250 12.4817 34.3313 248.732 54.2125
300 12.4817 33.9800 302.272 49.5100
350 10.1448 34.0944 349.722 45.5500
400 6.37824 34.3782 395.010 43.0750
450 1.93896 34.2942 455.044 40.1050
500 4.12536 33.6506 515.016 38.1250

EQUIPMENT LIST:

ITEM DESCRIPTION
MFR.
MODEL
S/N
CAL.DUE
Shaker Unholtz-Dickie T208-AMA    
Vibration Controller Data Physics SignalCalc 350    
Accelerometer Endevco 2211C 4860  
Oscilloscope Tektronix TDS 420 021700 04/28/01
LCR Meter Hewlett Packard 4274A 10045 06/23/01
Torque Gauge Sturtevant-Richmont DM 22-S 3038 08/22/01
Torgue Guage Sturtevant-Richmont DM 56-80 2660 08/22/01
High Voltage Tester Jennings Technology     08/09/01

 

Procedure:

The capacitor was cradled into a high voltage tester. Voltage was increased at a rate of about 500 Vrms per second. The specified test voltage of 15 kVp was applied across the unit and held for one minute. This procedure was performed post shock test with the unit set at maximum capacitance.

Equipment:

  • Jennings Technology high voltage tester
  • Jennings Technology barnacle detector

Result:

No barnacles were observed during testing. The unit was able to sustain high voltage.

Unit Date Code:
Beta 4 #3
TEST(s) CONDUCTED:
Shock

RESULTS:

PV4-500 Beta 4#7 11/20/2000
 
Acceleration (g)
     
  45 55 65 75 85 95 105 115      

C (pF)

0.2 0.3 0.3 0.4 0.4 0.5 0.5 0.7 Horizontal Orientation
0.1 0.2 0.2 0.3 0.3 0.3 0.4 0.4 Vertical


PV4-500 Beta 4#3 11/20/2000
# of Turns (360)
Capacitance (pF)
Torque (in-oz)
max-min
min-max
0 509.9    
1 476.5 24 21
2 442.4 26 20
3 407.9 27 17
4 373.3 28 17
5 338.7 29 14
6 304.1 29 14
7 269.3 30 13
8 234.3 31 13
9 199.6 31 13
10 164.7 31 13
11 129.7 31 13
12 94.8 31 13
13 60.1 31 12

EQUIPMENT LIST:

ITEM DESCRIPTION MFR MODEL S/N CAL.DUE
Shock Test Machine Impac 1818    
Isotron Conditioner Endevco 4416B AH33  
Accelerometer Endevco 25A CM11  
Mounting Wax Endevco 32279    
Oscilloscope Tektronix TDS 420 021700 04/28/01
LCR Meter Hewlett Packard 4274A 10045 06/23/01
Torque Guage Sturtevant-Richmont DM 22-S 3038 08/22/01
High Voltage Tester Jennings Technology     08/09/01

Conclusion:

The change in capacitance was measured after each of the eight drops with the unit in a horizontal position, and also after each of the eight drops in a vertical position. The change in capacitance of the unit was measured after each vibration test was performed-horizontal and vertical axes. The dielectric withstand voltage of the units were then tested. Torque versus turns and capacitance versus turns were measured and compared with the initial measurements. The capacitors did not sustain any visible damage and still meet their designed specifications.

 



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