CA3059

Manufacturer Part NumberCA3059
DescriptionZERO VOLTAGE CROSSING SWITCH
ManufacturerIntersil
CA3059 datasheet
 


Specifications of CA3059

Rohs StatusRoHS non-compliant  
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DC
LOGIC
COMMAND
PHOTO-COUPLED
ISOLATORS
FIGURE 60. SIMPLIFIED DIAGRAM OF A THREE PHASE HEATER CONTROL THAT EMPLOYS ZERO-VOLTAGE SYNCHRONOUS
SWITCHING IN THE STEADY STATE OPERATING CONDITIONS
1. The load should be connected in a three wire configuration
with the triacs placed external to the load; either delta or
wye arrangements may be used. Four wire loads in wye
configurations can be handled as three independent sin-
gle phase systems. Delta configurations in which a triac is
connected within each phase rather than in the incoming
lines can also be handled as three independent single
phase systems.
2. Only one logic command signal is available for the control
circuits. This signal must be electrically isolated from the
three phase power system.
3. Three separate triac gating signals are required.
4. For operation with resistive loads, the zero-voltage switch-
ing technique should be used to minimize any radio fre-
quency interference (RFI) that may be generated.
Isolation of DC Logic Circuitry
As explained earlier under Special Application Consider-
ations, isolation of the DC logic circuitry* from the AC line,
the triac, and the load circuit is often desirable even in many
single phase power control applications. In control circuits for
polyphase power systems, however, this type of isolation is
essential, because the common point of the DC logic cir-
cuitry cannot be referenced to a common line in all phases.
* The DC logic circuitry provides the low level electrical signal that
dictates the state of the load. For temperature controls, the DC log-
ic circuitry includes a temperature sensor for feedback. The Intersil
integrated circuit zero-voltage switch, when operated in the DC
mode with some additional circuitry, can replace the DC logic cir-
cuitry for temperature controls.
Application Note 6182
3 (SEE FIGURE 62) INPUT
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In the three phase circuits described in this section, photo optic
techniques (i.e., photo coupled isolators) are used to provide
the electrical isolation of the DC logic command signal from the
AC circuits and the load. The photo coupled isolators consist of
an infrared light emitting diode aimed at a silicon photo transis-
tor, coupled in a common package. The light emitting diode is
the input section, and the photo transistor is the output section.
The two components provide a voltage isolation typically of
1500V. Other isolation techniques, such as pulse transformers,
magnetoresistors, or reed relays, can also be used with some
circuit modifications.
Resistive Loads
Figure 59 illustrates the basic phase relationships of a bal-
anced three phase resistive load, such as may be used in
heater applications, in which the application of load power is
controlled by zero-voltage switching. The following condi-
tions are inherent in this type of application:
1. The phases are 120 degrees apart; consequently, all three
phases cannot be switched on simultaneously at zero voltage.
2. A single phase of a wye configuration type of three wire
system cannot be turned on.
3. Two phases must be turned on for initial starting of the
system. These two phases form a single phase circuit
which is out of phase with both of its component phases.
The single phase circuit leads on phase by 30 degrees
and lags the other phase by 30 degrees.
These conditions indicate that in order to maintain a system
in which no appreciable RFI is generated by the switching
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IN4003
R
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2
IN4003
R
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IN4003
3 PHASE
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D
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RESISTIVE LOAD
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(DELTA OR WYE)