Datasheet

Solid-State Switching Devices for Resistive Loads
Solid-State Contactors
General data
4/77
Siemens IC 10 · 2011
4
■ Overview
Solid-state contactors
The complete units consist of a solid-state relay plus optimized
heat sink, and are therefore ready to use. They offer defined
rated currents to make selection as easy as possible. Depend-
ing on the version, current intensities of up to 88 A are achieved.
Like all of our solid-state switching devices, one of their particu-
lar advantages is their compact and space-saving design.
With their insulated mounting foot they can easily be snapped
onto a standard mounting rail, or they can be mounted on sup-
port plates with fixing screws. This insulation enables them to be
used in circuits with protective extra-low voltage (PELV) or safety
extra-low voltage (SELV) in building management. For other ap-
plications, such as for extended personal safety, the heat sink
can be grounded through a screw terminal.
The solid-state contactors are available in 2 different versions:
• 3RF23 single-phase solid-state contactors
• 3RF24 three-phase solid-state contactors
Single-phase versions
The 3RF23 solid-state contactors can be expanded with various
function modules to adapt them to individual applications.
Version for resistive loads, "zero-point switching"
This standard version is often used for switching space heaters
on and off.
Version for inductive loads, "instantaneous switching"
In this version the solid-state contactor is specifically matched to
inductive loads. Whether it is a matter of frequent actuation of the
valves in a filling plant or starting and stopping small operating
mechanisms in packet distribution systems, operation is carried
out safely and noiselessly.
Special "Low noise" version
Thanks to a special control circuit, this special version can be
used in public networks up to 16 A without any additional mea-
sures, such as interference suppressor filters. As a result, in
terms of emitted interference, it conforms to limit value curve
class B according to EN 60947-4-3.
Special "Short-circuit proof" version
Skillful matching of the power semiconductor with the perfor-
mance capacity of the solid-state contactor means that "short-
circuit strength" can be achieved with a standard miniature cir-
cuit breaker. In combination with a B-type MCB or a conventional
line protection fuse, the result is a short-circuit proof feeder.
In order to achieve problem-free short-circuit protection by
means of miniature circuit breakers, however, certain boundary
conditions must be observed. As the magnitude and duration of
the short-circuit current are determined not only by the short-cir-
cuit breaking response of the miniature circuit breaker but also
the properties of the wiring system, such as the internal resis-
tance of the input to the network and damping by controls and
cables, particular attention must also be paid to these parame-
ters. The necessary cable lengths are therefore shown for the
main factor, the line resistance, in the table below.
The following miniature circuit breakers with a B characteristic
and 10 kA or 6 kA breaking capacity protect the 3RF23..-.DA..
solid-state contactors in the event of short circuits on the load
and the specified conductor cross-sections and lengths:
1)
The miniature circuit breakers can be used up to a maximum rated voltage
of 480 V!
The setup and installation above can also be used for the solid-
state relays with a I
2
t value of at least 6600 A
2
s.
Three-phase versions
The three-phase solid-state contactors for resistive loads up to
50 A are available with
• Two-phase control (suitable in particular for circuits without
connection to the neutral conductor) and
• Three-phase control (suitable for star circuits with connection
to the neutral conductor or for applications in which the system
requires all phases to be switched)
The converter function module can be snapped onto both ver-
sions for the simple power control of AC loads by means of ana-
log signals.
• Check the correct contactor size with the aid of the rated cur-
rent diagram, taking account of the installation conditions
Rated current of the
miniature circuit
breaker
Example of
type
1)
Max. conductor
cross-section
Minimum cable
length from
contactor to
load
6 A 5SY4 106-6,
5SX2 106-6
1 mm
2
5 m
10 A 5SY4 110-6,
5SX2 110-6
1.5 mm
2
8 m
16 A 5SY4 116-6,
5SX2 116-6
1.5 mm
2
12 m
16 A 5SY4 116-6,
5SX2 116-6
2.5 mm
2
20 m
20 A 5SY4 120-6,
5SX2 120-6
2.5 mm
2
20 m
25 A 5SY4 125-6,
5SX2 125-6
2.5 mm
2
26 m
NSB0_01473b
K1
L2
L1
L1
L3
N
2
T
F1
I,A
R1
F2
K1
L2
L1
L1
L3
N
2
T
F1
I,A
R1
line
3/N/PE 50 Hz 230/400 V 3/N/PE 50 Hz 230/400 V
line line
© Siemens AG 2010