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RC NETWORKS SALES GUIDE
®
RC NETWORKS
SALES GUIDE
Recent developments in electronic equipment have shown
the following trends: Increasing demands for numerical control machines,
robotics and technically advanced appliances are requiring
progressive electronic technologies. When employing integrated circuit and microcomputer
technology, todays equipment is required to perform
multifunctions in limited size. The denser the installation of components, the more
the components must be miniaturized and of lighter weight.
As a result, the following problems arise: Functional limits of magnetic relays and switches
have narrowed due to increasing contact amperage. Miniaturization of electronic components has reduced
their dielectric strength. Circuit noise has increased as a result of the coexistence
of signal and power lines. Safety standards for electronic equipment and components
have become increasingly restrictive.
Some key factors affecting circuit performance are: Arcing between relay and switch contacts cause pitting
and whiskers resulting in premature contact failure. Contact arcing results in high frequency noise and
abnormal high voltages. The generation of back electromotive force (EMF) is due to
the inductance of loads present. The occurrence of high frequency noise is the result of
contact chatter in magnetic relays and switches.
Back EMF, due to inductance, affects Silicon Control
Rectifiers (SCRs) and Solid-State Relays (SSRs) and can result
in the breakdown of other semiconductor devices. Power line
surges must also be carefully considered. Either may be a
contributing factor in equipment malfunctions, failures and
in extreme cases of fire and/or electrical shock.
To illustrate these factors, consider that relay contact chatter
is capable of inducing oscillations of several KHz, contact
arcing frequencies of several MHz and amplitudes 10 to 20
times normal circuit voltages. Voltage surges from external
sources may approach thousands of volts.
To protect electronic equipment against costly failures
or malfunctions, Electrocube has developed advanced
components to suppress contact arcing and filter unwanted
electrical noise.
I N T R O D U C T I O N T O R C N E T W O R K S
G E N E R A L C O N S T R U C T I O N
S A F E T Y S TA N D A R D S
A P P L I C AT I O N S
C U S T O M D E S I G N S
RC Networks are easily selectable electronic components
designed to prevent or substantially minimize the
occurrence of arcing and noise generation in relay and
switch contacts.
RC Networks consist of specially designed capacitors and
resistors connected in series. Spark discharges and induced
noise are absorbed over a wide range by the accumulation
characteristic and impedance of the capacitor, while the RC
time constant delays and averages surge voltage and
oscillations.
RC Networks must have the capacity to store surge voltages
and current energy and afford protection against inductively
induced potentials. The dielectric material of Electrocubes
capacitors, used in RC Networks, affords a very high degree of
voltage withstand strength. All resistors are non-inductive
types to insure a high degree of protection against pulse
potentials. To provide additional protection for equipment and
users, especially when these components are used in their
applications, all Electrocube RC Networks are packaged in
cases which meet or exceed the flammability requirements of
UL94VO.
Electrocubes RC Networks are UL and ULC approved.
Self-declaration of CE mark is available upon request. Protection for contacts and from noise during switching
operations of equipment such as radio, TV, copiers,
mixers, coffee grinders, washing machines, dryers, tool
machine equipment, packaging machinery, etc. Protection of electronic instruments during operation of
relays, solenoids, motors, etc. Electrical noise protection of semiconductor devices
during control of triacs, thyristors, motors, welders,
illumination equipment, etc
Electrocube offers many years of experience in the design
and manufacture of standard RC Networks, as well as special
units to meet customer requirements. For custom applications,
consult the factory direct to assist in the design, production
and delivery of your special needs.
1307 S. Myrtle Ave. Monrovia, CA 91016 TEL: (626) 301-0122 FAX: (626) 357-8099
e-mail: sales@electrocube.com Internet: www.electrocube.com (IR: 9/99)
® ®
RC NETWORKS
ENGINEERING GUIDE
CIRCUIT ACTIVATION RESISTOR
TIMES/MINUTE
WAT TAGE
1-3
1/2
4-5
1
6-9
2
10-15
5
>15
10
E F F E C T O F R C N E T W O R K S
A P P L I C AT I O N E X A M P L E S
D E T E R M I N I N G R C VA L U E
At the moment of switch opening, the RC combination
absorbs and suppresses the energy of the arc by letting it
bypass the switch.
The RC combination absorbs the high frequency oscillations
caused by mechanical vibrations such as relay contact chattering.
Similarly, the oscillations created by arcing are also averaged and
suppressed by the RC combination regardless of their origin.
With back electromotive force due to inductance, the surge
voltage peak is suppressed by conducting it through the RC
circuit on the low impedance side. the peak is absorbed by the
capacitance of RC. The waveform is averaged and smoothed
by the time constant of the RC; thus generated noise is
eliminated or substantially minimized.
The RC combination allows the dv/dt of the on and off
operation of thyristors or similar devices to decrease; thus surge
voltages are suppressed and semiconductor elements are
protected. Even in the case of zero crossing circuits, such as AC
circuits, protection is necessary since harmonic noise occurs
when there is a gap between phases of current and voltage of
the load circuit.
In general, the calculated RC value is difficult to determine
using the following formula. This is due to contributing factors
such as equipment wiring and component locations which can
vary from machine to machine.
The best way to determine the values needed is to obtain a
storage oscilloscope and match combinations of resistors and
capacitors while viewing the amount of spike reduction on the
oscilloscope. The user should change the combination of R & C
until the optimum spike reduction is achieved.
Electrocube has determined that the best overall combination is
0.47-.50 Mfd @ 220
W
. This combination seems to work for 90%
of the applications. The voltage should be selected for the
normal DC or AC voltages, however, the designer must take
into consideration the peak voltages involved.
The resistor wattage depends upon the number of times per
minute the circuit is activated. As a general rule of thumb, the
following chart should be considered.
The chart and formula are guidelines to give the user a starting
point from which to work. The final selection must be evaluated
in the application to determine its acceptability.
DAMPING OSCILLATION
BACK ELECTROMOTIVE FORCE SUPPRESSION
DV/DT SUPPRESSION
ARC SUPPRESSION
Standard example in AC circuits
Standard example in DC circuits
Standard example in DC circuits
For phase control circuits employing
SCR or TRIAC, etc.
1307 S. Myrtle Ave. Monrovia, CA 91016 TEL: (626) 301-0122 FAX: (626) 357-8099
e-mail: sales@electrocube.com Internet: www.electrocube.com (IR: 9/99)
®
E ®
RC NETWORKS
SINGLE-PHASE
RESISTANCE PEAK
CAPACITY OHMS RATED PULSE A B
C #20 AWG TINNED #18 AWG MTW
MFD 10%
VOLTAGE
VOLTAGE IN.
IN. IN. SOLID WIRE 3 LEADS
0.5±10%
22
300V
1.00
.38
.63
RG1780-1
RG1983-1
0.5±10%
33
300V
1.00
.38
.63
RG1780-2
RG1983-2
0.5±10%
47
300V
1.00
.38
.63
RG1780-3
RG1983-3
0.5±10%
68
300V
1.00
.38
.63
RG1780-4
RG1983-4
0.5±10%
82
300V
1.00
.38
.63
RG1780-5
RG1983-5
0.5±10%
100
300V
1.00
.38
.63
RG1780-6
RG1983-6
0.5±10%
150
300V
1.00
.38
.63
RG1780-7
RG1983-7
0.5±10%
220
300V
1.00
.38
.63
RG1780-8
RG1983-8
0.5±10%
330
300V
1.00
.38
.63
RG1780-9
RG1983-9
0.5±10%
470
300V
1.00
.38
.63
RG1780-10
RG1983-10
0.5±10%
680
300V
1.00
.38
.63
RG1780-11
RG1983-11
1.0±10%
22
300V
1.00
.50
.75
RG1781-1
RG2030-1
1.0±10%
33
300V
1.00
.50
.75
RG1781-2
RG2030-2
1.0±10%
47
300V
1.00
.50
.75
RG1781-3
RG2030-3
1.0±10%
68
300V
1.00
.50
.75
RG1781-4
RG2030-4
1.0±10%
82
300V
1.00
.50
.75
RG1781-5
RG2030-5
1.0±10%
100
300V
1.00
.50
.75
RG1781-6
RG2030-6
1.0±10%
150
300V
1.00
.50
.75
RG1781-7
RG2030-7
1.0±10%
220
300V
1.00
.50
.75
RG1781-8
RG2030-8
1.0±10%
330
300V
1.00
.50
.75
RG1781-9
RG2030-9
1.0±10%
470
300V
1.00
.50
.75
RG1781-10
RG2030-10
1.0±10%
680
300V
1.00
.50
.75
RG1781-11
RG2030-11
0.1±20%
22
900V
1.00
.38
.63
RG1782-1
RG2031-1
0.1±20%
33
900V
1.00
.38
.63
RG1782-2
RG2031-2
0.1±20%
47
900V
1.00
.38
.63
RG1782-3
RG2031-3
0.1±20%
68
900V
1.00
.38
.63
RG1782-4
RG2031-4
0.1±20%
82
900V
1.00
.38
.63
RG1782-5
RG2031-5
0.1±20%
100
900V
1.00
.38
.63
RG1782-6
RG2031-6
0.1±20%
150
900V
1.00
.38
.63
RG1782-7
RG2031-7
0.1±20%
220
900V
1.00
.38
.63
RG1782-8
RG2031-8
0.1±20%
330
900V
1.00
.38
.63
RG1782-9
RG2031-9
0.1±20%
470
900V
1.00
.38
.63
RG1782-10
RG2031-10
0.1±20%
680
900V
1.00
.38
.63
RG1782-11
RG2031-11
0.25±20%
22
900V
1.00
.50
.75
RG1783-1
RG1988-1
0.25±20%
33
900V
1.00
.50
.75
RG1783-2
RG1988-2
0.25±20%
47
900V
1.00
.50
.75
RG1783-3
RG1988-3
0.25±20%
68
900V
1.00
.50
.75
RG1783-4
RG1988-4
0.25±20