as accessories for
the power spectrum up to 75
HP. The desired combination
starter can thus be assembled
quickly and economically by
the customer. A time saving is
also achieved with the link
modules as unlike with con-
ventional wiring systems there
is no need to rectify possible
wiring errors.
As a combination starter rated
for tap conductor protection for
group installation the 3RV1
MSP is responsible for overload
and short-circuit protection in
the motor circuit. Back-up pro-
tective devices, such as fuses
or SIEMENS Sentron circuit
breakers are required as per
NEC 430-53 guidelines for
group installations for multiple
motor applications
The 3RT contactor is ideal for
extremely complex switching
tasks requiring durable compo-
nents.
The permissible ambient tem-
perature is 60

°C with butt-
mounting and without derating
(70

°C possible subject to cer-
tain restrictions).
3RA1 combination starters are
available for motors up to 75 Hp
at 460 V AC and setting ranges
from 0.14 A to 100 A.
3RA1 combination starters are
supplied in four different
sizes:
Operating conditions
3RA1 combination starters are
climate-proof. They are intended
for use in enclosed rooms in
which no severe conditions
(such as dust, caustic vapors,
hazardous gases) prevail. Suita-
ble enclosures must be pro-
vided for installation in dusty
and damp locations. Accessories
The accessories for the special
equipment, such as auxiliary
contacts and undervoltage trips,
can also be used for the 3RA1
combination starters.
In addition, certain accessories
have been optimized for the
combination starters. They
include the top-connected,
transverse auxiliary contact on
the MSP with one changeover
contact or one NO contact +
one NC contact. Special auxil-
iary contact blocks that can be
snapped on from below are
available for the contactor.
These two accessories enable
the combination starters to be
wired easily without having to
route cables via the equipment.
The special accessories for
3RA1 combination starters take
the form of link modules for
3RV1 MSPs and 3RT1 contac-
tors. Technical data
For technical data, see pages
5/27 and 5/28. Additional details
are contained in the respective
tables for the 3RV1 MSPs and
3RT1 contactors. Configuration
Overload tripping times
All the 3RA1 combination start-
ers described here are
designed for normal starting, in
other words for overload tripping
times of less than 10 s
(CLASS 10). At rated-load oper-
ating temperature the tripping
times are shorter, depending on
the particular equipment and the
setting range. The exact values
can be derived from the tripping
characteristics of the MSPs.
Classification types
DIN VDE 0660 Part 102 and
IEC 60 947-4-1 make a distinc-
tion between two different types
of coordination (types 1 and 2).
Any short-circuits that occur are
cleared safely by both types of
coordination. The only differ-
ences concern the extent of the
damage caused to the equip-
ment by a short-circuit.
IEC Type of coordination 1
The combination starter may be
non-operational after a short-cir-
cuit has been cleared. Damage
to the contactor or to the over-
load relay is permissible. In 3RA
load feeders, the MSP itself
always achieves type of coordi-
nation 2.
IEC Type of coordination 2
There must be no damage to the
overload trip or to any other
components after a short-circuit
has been cleared. The 3RA1
combination starter can resume
operation without needing to be
renewed. At most, it is permissi-
ble to weld the contactor con-
tacts if they can be
disconnected easily without any
significant deformation. Mounting
Complete equipment
The 3RA1 combination starters
can be ordered as complete
equipment for direct starting or
for reversing mode. Control sup-
ply voltages of 50 Hz AC 230 V
or DC 24 V and assembly on a
35 mm standard mounting rail or
in a 40 or 60 mm busbar system
are possible.
Special equipment for customer
assembly can be ordered if
other rated control supply volt-
ages are required. The link mod-
ules simplify customer assembly
of the load feeders.
The corresponding distances
from earthed or live parts, as
detailed in the technical data,
must be observed.
Customer assembly
The standard devices can be
combined optimally in terms of
both technical data and dimen-
sions, thanks to the modular sys-
tem of the SIRIUS series.
The combination starters can
thus be assembled easily by the
customer. It is simply necessary
to assemble the standard 3RV1
MSP and 3RT1 contactor and
the appropriate link module
together.
For the order numbers for spe-
cial equipment and link mod-
ules, see the selection and
ordering data.
For the link modules for direct
starting or reversing mode and
assembly on a standard mount-
ing rail or busbar, see accesso-
ries.
If a MSP with a rotary operating
mechanism is required for the
lower setting ranges up to 12 A,
the S0 MSP can also be assem-
bled with an S00 contactor. A
special connecting module is
available for this purpose.
For the installation of feeders, it
is imperative to use standard rail
adapters, as from size S2 for
direct starting and as from size
S0 for reversing, to ensure the
necessary mechanical strength.
A standard rail adapter is not
necessary if a busbar adapter is
used.
Assembly
3RA1 combination starters are
available for assembly on stand-
ard mounting rails in accord-
ance with EN 50 022-35 x 15 or
on busbar adapters with a bus-
bar centre-line spacing of 40 or
60 mm and a busbar thickness
of 5 or 10 mm.
The combination starters are
also suitable for screw fixing.
Size S00 and S0 can be
screwed on with the aid of plug-
in clips (see accessories on
page 5/22).
Size
Overall
width
Max.
rated
current
I
n max
For
three-
phase
motors
up to
mm
A
HP
S00
S0
S2
S3
45
45
55
70
8
22
50
100
5
15
40
75
Siemens Energy & Automation, Inc.
Industrial Controls Catalog
3RA1
up to 100 A
Combination Starters & Starters for Group Installation
SIRIUS
05_Sec (001-046).qxd 07/28/03 04:01 PM Page 5/29