Accessories and Spare Parts
For 3RT, 3RH Contactors and Contactor Relays
Accessories for 3RT, 3RH contactors and
contactor relays
If the command devices are upstream of the OFF-delay device
4000 V
in the circuit, the OFF-delay takes effect with every opening
operation. If the opening operation is downstream of the OFF-
V
delay device, an OFF-delay only applies in the event of failure of
the mains voltage.
Operation
In the case of the versions for rated control supply voltages of
110 V and 230 V, either AC voltage or DC voltage can be applied
on the line side, whereas the variant for 24 V is designed for
DC operation only.
400 V
500 ms
t
A DC-operated contactor is connected to the output in
accordance with the input voltage that is applied.
Capacitive input to various analog and digital signals makes it
necessary to suppress interference in the load circuit.
The mean value of the OFF-delay is approximately 1.5 times the
specified minimum time.
Reducing contact arcing
Surge suppressors
• Without LED (also for Cage Clamp terminals)
Sizes S00, S0, S2, S3, S6 to S12
• With LED (also for Cage Clamp terminals)
Size S00
The connection between the main conducting path and the EMC
interference suppression module enables contact arcing, which
is responsible for contact erosion and the majority of clicking
noises, to be reduced; this in turn is conducive to an electromag-
netically compatible design.
All 3RT1 contactors and 3RH1 contactor relays can be retrofitted
with RC elements or varistors for damping opening surges in the
coil. Diodes or diode assemblies (comprising noise suppression
diodes and Zener diodes for rapid switch-off) can be used.
Higher operational reliability
Since the EMC interference suppression module achieves a
significant reduction in radio-frequency components and the
voltage level in three phases, the contact endurance is also
improved considerably. This makes an important contribution
towards enhancing the reliability and availability of the system as
a whole.
The surge suppressors are plugged onto the front of size S00
contactors. Space is provided for them next to a snap-on
auxiliary switch block.
With all size S0 to S3 contactors, varistors, RC elements and
diode assemblies can be plugged on directly at the coil
terminals, either on the top or underneath.
Dispensing with fine graduations
There is no need for fine graduations within each performance
class, as smaller motors inherently have a higher inductance, so
that one solution for all fixed-speed drives up to 5.5 kW is
adequate.
The plug-in direction of the diodes and diode assemblies is
determined by a coding device.
Coupling relays are supplied either without overvoltage
damping or with a varistor or diode connected as standard,
according to the version.
Two electrical variants are available:
• The advantages of the RC circuit lie mainly in the reduction in
the rate of rise and in its RF damping ability. The selected
values ensure effective interference suppression over a wide
range.
Note:
The OFF-delay times of the NO contacts and the ON-delay times
of the NC contacts increase if the contactor coils are damped
against voltage peaks (noise suppression diode 6 to 10 times;
diode assemblies 2 to 6 times, varistor +2 to 5 ms).
V
Electromagnetic interference suppression module, 3-phase
for size S00 contactors
930 V
400 V
500 ms
t
• The varistor circuit can absorb a high energy level and can
also be used for frequencies ranging from 10 to 400 Hz
(closed-loop controlled drives). There is no limiting below the
knee-point voltage, however.
V
A so-called counter-e.m.f. (electromotive force) is produced
when motors or various inductive loads are turned off. Voltage
peaks of up to 4000 V may occur as a result, with a frequency
spectrum from 1 kHz to 10 MHz and a rate of voltage variation
from 0.1 to 20 V/ns.
950 V
400 V
500 ms
t
Siemens LV 1 · 2006
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SIEMENS [ Siemens Semiconductor Group ]
