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Defibrillator capacitor

Application of Film Capacitor
in Cardiac Defibrillator

Defibrillation is the only effective way to treat sudden cardiac death
Cardiac defibrillator is currently widely used clinical rescue equipment. It uses pulsed current to act on the heart, implement electric shock therapy, eliminate arrhythmia, and restore the heart to sinus rhythm.

death  1

Its working principle mostly adopts RLC damping discharge method, as shown in the figure:

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Defibrilla
Typical data
Energy 100~500J
Voltage 2000~5000VDC
Capacitance 32~200UF
Discharge load  20Ω/50Ω/100Ω
Maximum pulse current 100~1kA

First charge the energy storage capacitor C to make the capacitor obtain a certain amount of energy. During defibrillation treatment, C, inductance L and human body (load) are connected in series to perform electric shock treatment on the human heart

● Stored energy

The electric energy charged into the energy storage device before the defibrillation shock. The relationship between the energy stored in the capacitor and the voltage of the capacitor:

E=½cu²

For the application in the defibrillator, the CRE film capacitor has a special customized design, which has higher performance advantages:

Compared with the 10,000 times service life in the market, the special film structure design makes the charging and discharging life times more than 30,000 times

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Taking into account the application of uncertain and harsh environment such as outdoor, it adopts special anti-humidity and high temperature resistance design, which has higher reliability

Especially for the small volume design of the external automatic defibrillator (AED) (such as handheld requirements), using high energy density materials, the volume and weight are 50% smaller than the conventional design

Application 1:

A certain 360J defibrillator model, selecting capacitor model:195UF/2200VDC

SPECIFICATION:

1、RATED VOLTAGE (Un) : 2200VDC
2、RATED CAPACITANCE:200MFD
3、TOLERANCE OF CAPACITANCE: 士5%(J)AT 1KHz,+25℃
4、OPERATION TEMPERATURE:-25℃~+70℃
5、DISSIPATION FACTOR(DF): ≤0.0060 AT 100Hz,+25℃
6、TEST VOLTAGE: TERMINAL TO TERMINAL:2300VDC/10SEC
7、INSULATION RESISTANCE: AFTER 300 SECONDS ELECTRIFICATION 100VDC,AT +25℃
TERMINAL TO TERMINAL:THE MINIUNM IR SHALL BE≥5000SEC
TERMINAL TO CASE:THE MINIUNM IR SHALL BE≥3000M 2
8、MAX. PUSLE RISE TIME (DV/DT) : 5V/ us
9、PEAK CURRENT MAX.:1000AMPS AT +25℃
10、PULSE DISCHARGE TEST WITH RATE PEAK CURRENT 440A,CHARGE VOLTAGE 2200V 35 SHOTS
11、CASE MATERIAL:FR-PP,UL94 V-o,GRAY-WHITE
12、POTTING MATERIAL: FR-EPOXY,UL94 V-o,GRAY-WHITE
13、LEADS: 1x1 UL 3239 22AWG 150℃, WHITE AND RED
14、TERMINAL:YT396(A)(396-03JR)
15、EXPECTED LIFE 2500 DISCHARGES WTHT A LOAD OF 10 Q
16、DATE CODE:DATE CODE HAS 4 DIGITS AS FOLLOWs:

Take our products and two common manufacturers in the market to do the same test comparison. Under the application conditions of high temperature and humidity, our products have a longer life.

Test conditions:
1.Static test conditions: record capacity, loss, equivalent series resistance. The static parameters are recorded every 10,000 times of charging and discharging. In order to ensure the accuracy of data recording, the capacitor temperature should be as close as possible to the ambient temperature when collecting. The test is carried out at a temperature difference of ≤5 ℃.
2.Dynamic test conditions: environment 55 ℃ 95%, test terminal voltage 2200V.DC, charge time 4S, discharge time 1S, voltage change rate DV/DT=4.7V/μS, pulse peak current 940A, charge and discharge 20000 times. The test acceleration pulse current is 1.6 times of our company's nominal current (585A).
3. Test process: Capacitor static parameters before test.

NO. Manufacturer @100Hz @1000Hz
Capacitance(uF) Loss Tangent ESR(mΩ)
1# img FA** 192.671 0.00678 55.6
2# CRE 192.452 0.00218 15.9
3# EI** 190.821 0.00428 34.84

 

● Connect the capacitor to be tested to the test power supply, set the test parameters, and adjust the temperature and humidity test chamber to the specified test environment conditions.

specified 1
specified 2
impulse 1
impulse 2

● Start the impulse discharge test on the capacitor according to the set parameters:

● During the test, if the voltage fluctuates abnormally or the capacitor breakdown occurs, the test should be stopped immediately, and static data acquisition and analysis of the capacitor should be performed to confirm whether the test is necessary to continue.

Charging and discharging times 1#FA**  
C(uF)@100Hz tgδ@100Hz ESR(mΩ)) Note
Initial value 192.671 0.00678 55.6 After 492 times of test, capacitor terminal voltage dropp-ed to 1720VDC, capacitance decreased by 8.17%. It is not suitable to continue the test.
492 times 176.932 0.00584 51.3
/ Stop the test 
Rate of change -8.17% Decline -7.73%
Charging and discharging times 2#CRE  
C(uF)@100Hz tgδ@100Hz ESR(mΩ)) Note
Initial value 192.452 0.00218 15.9 The capacitance decreased by 0.72% for1W times and 2.15% for 2W times of test.No obv-ious abnormality of capa-citor.Test continued. 
10000 veces 191.07 0.0019 14.86
20000 veces 188.315 0.0017 14.22
30000 veces In ongoing test
Rate of change -0.72% -2.15% Decline -6.54% -10.57%
Charging and discharging times 3#EI**  
C(uF)@100Hz tgδ@100Hz ESR(mΩ)) Note
Initial value 192.452 0.00218 15.9 After 257 times of test, the cap-acitance decreased by 1.89%.The capacitor terminal voltage dropped to zero.The capacitor presents a short circuit state, a-nd the test stopped.
257 veces 191.07 0.0019 14.86
/ Stop test
Rate of change -1.89% The tangent of loss Angle is abnormal Anormal 

Application 2:

This program is specially designed for the small size of a 180J handheld external automatic defibrillator (AED), the specification is 100UF/2000VDC.

  Size(mm) Volume(m³)
Conventional scheme  Φ50*115 225.8
Miniaturization scheme  Φ35*120 115
After the miniaturized design, the volume and weight are 50% smaller than the conventional design.

 

miniaturized

Comparison of miniaturized design and original size

By comparing the parameters of the product after 5000 times of impulsive discharge, the capacity attenuation is only less than 3%, which can guarantee its long-term service life.

  Capacitance before test Capacitance after test Loss before test Loss after test
1 95.38 93.80 0.00236 0.00243
2 95.56 94.21 0.00241 0.00238
3 96.58 95.33 0.00239 0.00243
4 95.53 92.81 0.00244 0.00241

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