ISKRA MANUFACTURES AND SUPPLIES A WIDE RANGE OF POWER ELECTRONIC CAPACITORS WHICH CAN BE USED FOR

VARIOUS FUNCTIONS IN ELECTRIC CIRCUITS. THEY ARE MOST COMMONLY USED IN FREQUENCY OR VOLTAGE INVERTERS,

UNINTERRUPTIBLE POWER SUPPLIES, MOTOR DRIVES, WELDING EQUIPMENT, WIND AND SOLAR POWER SYSTEMS.

A TYPICAL SWITCHING-MODE POWER SUPPLY IS SHOWN IN THE FIGURE BELOW. DC LINK CAPACITORS AT POSITION C1

ARE USED FOR DC VOLTAGE SMOOTHING. CAPACITORS AT POSITION C2 ARE SNUBBER CAPACITORS. WHEN A SWITCH

OPENS, THEY ELIMINATE VOLTAGE SPIKES CAUSED BY CIRCUIT INDUCTANCE. AC FILTERING CAPACITORS AT POSITION C3

ARE USED IN INPUT/OUTPUT LOW-PASS LC FILTERS.

THE AC/DC GENERAL PURPOSE CAPACITORS MAY BE USED IN AC OR DC APPLICATIONS.

AC/DCDC/AC

C2C1C2C3

PLACE

DC LINK

ENERGY STORAGE

BYPASS

DECOUPLING

SMOOTHING

KNG2047

KNG2048

KNG3047

KNG3048

KNG4910

KNG4914

NG1910

KNG1914

KNO19Ax

KNO19Bx

KNI5048

(SINGLE PHASE)

KNI4053

(THREE PHASE)

DC LINK EV

KNO1910

KNO1914

KNB1910

KNB1914

WITH SCREWS

FOR PCB

TERMINAL BLOCK

FOR PCB

WITH LUGS

SNUBBERING

RESONANT

AC FILTERING

FUNCTION

TYPE

DESIGNATION

MOUNTINGPAGE

CAPACITOR SELECTION GUIDE

BLOCK DIAGRAM

TABLE OF CONTENTS

Snubber capacitors

Dimensions

DC link capacitors and snubbers

U RATED DC VOLTAGE

NDC

MAXIMUM OPERATING PEAK VOLTAGE OF EITHER

POLARITY BUT OF A NON-REVERSING TYPE WAVEFORM

FOR WHICH THE CAPACITOR HAS BEEN DESIGNED.

–

U RATED RMS VOLTAGE

rms

ROOT MEAN SQUARE OF MAX. PERMISSIBLE VALUE OF

SINUSOIDAL AC VOLTAGE IN CONTINUOUS OPERATION.

–

U RATED AC VOLTAGE

MAXIMUM OPERATING PEAK RECURRENT VOLTAGE OF

EITHER POLARITY OF A REVERSING TYPE WAVEFORM FOR

WHICH THE CAPACITOR HAS BEEN DESIGNED.

–

U RIPPLE VOLTAGE

PEAK-TO-PEAK ALTERNATING COMPONENT OF THE

UNIDIRECTIONAL VOLTAGE.

–

C RATED CAPACITANCE

NOMINAL VALUE OF CAPACITANCE MEASURED AT 20 °C.

–

I MAXIMUM CURRENT

max

MAXIMUM RMS CURRENT FOR CONTINUOUS OPERATION.

–

(dU/dt) MAXIMUM RATE OF VOLTAGE RISE

max

MAXIMUM PERMISSIBLE REPETITIVE RATE OF VOLTAGE

RISE OF THE OPERATIONAL VOLTAGE.

–

Î MAXIMUM PEAK CURRENT

MAXIMUM REPETITIVE PEAK CURRENT THAT CAN OCCUR

DURING CONTINUOUS OPERATION.

Î = C x (dU/dt)

max

–

Î MAXIMUM SURGE CURRENT

PEAK NON-REPETITIVE CURRENT INDUCED BY SWITCHING

OR ANY OTHER DISTURBANCE OF THE SYSTEM WHICH IS

ALLOWED FOR A LIMITED NUMBER OF TIMES, FOR

DURATIONS SHORTER THAN THE BASIC PERIOD.

Î = C x (dU/dt)

–

tan() TANGENT OF THE LOSS ANGLE OF A CAPACITOR

RATIO BETWEEN EQUIVALENT SERIES RESISTANCE AND

THE CAPACITIVE REACTANCE OF A CAPACITOR AT A

SPECIFIED SINUSOIDAL ALTERNATING VOLTAGE,

FREQUENCY AND TEMPERATURE.

tan(δ)= ESR x ω x C = tan(δ) + R x

tan(δ)= DIELECTRIC LOSS FACTOR

δ –

ωx C

R SERIES RESISTANCE

EFFECTIVE OHMIC RESISTANCE OF THE CONDUCTOR OF A

CAPACITOR UNDER SPECIFIED OPERATING CONDITIONS.

–

ESR EQUIVALENT SERIES RESISTANCE OF A

CAPACITOR

EFFECTIVE RESISTANCE WHICH, IF CONNECTED IN SERIES

WITH AN IDEAL CAPACITOR OF CAPACITANCE VALUE

EQUAL TO THAT OF THE CAPACITOR IN QUESTION,

WOULD HAVE A POWER LOSS EQUAL TO ACTIVE POWER

DISSIPATED IN THAT CAPACITOR UNDER SPECIFIED

OPERATING CONDITIONS.

–

ESR = tan(δ) / (ω x C) + R

L SELF-INDUCTANCE

THE SUM OF ALL INDUCTIVE ELEMENTS WHICH ARE

CONTAINED IN A CAPACITOR.

–

P DISSIPATED POWER

diss

ACTIVE POWER DISSIPATED IN THE CAPACITOR.

P = I x ESR

dissmax

–

θ– AMBIENT TEMPERATURE

amb

TEMPERATURE MEASURED FROM THE DISTANCE OF

APPROXIMATELY 0.1 m AND AT TWO-THIRDS OF THE

HEIGHT OF THE CAPACITOR.

θ LOWEST OPERATING TEMPERATURE

min

LOWEST TEMPERATURE OF THE DIELECTRIC AT WHICH

THE CAPACITOR MAY BE ENERGIZED.

–

θ– MAXIMUM OPERATING TEMPERATURE

max

HIGHEST TEMPERATURE OF THE CASE AT WHICH THE

CAPACITOR MAY BE OPERATED.

R THERMAL RESISTANCE

THERMAL RESISTANCE INDICATES HOW MANY DEGREES

THE TEMPERATURE OF THE CAPACITOR RISES AT THE HOT

SPOT IN RELATION TO THE DISSIPATION LOSSES.

–

Δ – CONTAINER TEMPERATURE RISE

case

DIFFERENCE BETWEEN THE TEMPERATURE OF THE

HOTTEST POINT OF THE CONTAINER AND THE

TEMPERATURE OF THE COOLING AIR.

θ= θ + P x R

hs ambdissth

– HOT-SPOT TEMPERATURE

TEMPERATURE AT THE HOTTEST SPOT INSIDE THE

CAPACITOR.

P= (θ - θ) / R

max hsamb th

– MAXIMUM POWER LOSS

max

MAXIMUM PERMISSIBLE POWER DISSIPATION FOR

CONTINUOUS OPERATION.

TERMS AND DEFINITIONS

POWER ELECTRONIC CAPACITORS

APPLICATIONS

WIND PLANTS

WELDING EQUIPMENT

UPS SYSTEMS

HYBRID VEHICLES

SOLAR POWER PLANTS

FREQUENCY INVERTERS

DC (AC)/AC (DC)

INVERTER

IGBT MODULE

DC/AC

INVERTER

DC/AC

INVERTER

DC (AC)/AC (DC)

INVERTER

DC (AC)/AC (DC)

INVERTER

Snubber capacitors

Dimensions

DC link capacitors and snubbers