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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 5½ 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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