IEC Overload Relays
SIRIUS 3RU11 Bimetallic Class 10 Overload Relays
3RU11 overload relays belong to the new gen-
eration of SIRIUS 3R control products. The
3RU11 overload relays replace the highly suc-
cessful 3UA5 and 3UA7 devices. Outstanding
features of the new overload relays include
long term stability and long service life. The
overload relays are optimally matched, both
electrically and mechanically, to the 3RT10
contactors. They can also be mounted as a
single unit with the use of a separate mount-
ing bracket. 3RU11 overload relays cannot be
mounted onto 3TF contactors.
The 3RU11 overload relays are available in four
distinct frame sizes up to 100A. The selection
charts in this catalog refer to the different
frame sizes by their catalog numbers, i.e.
3RU111, 3RU112, 3RU113, and 3RU114. The
sixth character in the part number designates
the frame size. This “size number” is consis-
tent with, and matches up to, the same four
frame sizes of the other IEC products in this
catalog. However, it is important to note that
other SIRIUS 3R catalog versions in circulation
throughout the world refer to these four sizes
as S00, S0, S2, and S3 respectively. It is a
possibility that these four frame size refer-
ences (S00, S0, S2, and S3) may appear on
product labels as well.
3RU11 overload relays provide overload pro-
tection for three-phase inductive motors with
rated currents of up to 100A (75HP, AC-3,
480V). They are used in conjunction with
3RT10 contactors to form motor starters.
Thanks to the newly integrated bimetal and
continuous temperature compensation, these
devices can be used without derating at an
ambient temperature of up to 60°C (140°F).
Use up to 70°C (158°F) is possible with derat-
ing. (See Siemens Industrial Control Products
Catalog - CPPC-06000).
The overload relays are equipped with a NC
contact for de-energizing the contactor and a
NO contact for signalling an overload trip.
The breaking capacity of the switching con-
tacts is very high so that the contactor coils
can be switched directly.
The 3RU11 overload relays are designed in
accordance with trip class 10, i.e. trips in less
than 10 seconds at 6 times the trip current
3RU111 Overload Relay
Phase failure sensitivity
A phase failure sensitivity function is integrat-
ed in order to provide increased protection in
the event of a phase failure, i.e. faster tripping
in the event of a single-phase condition.
Setting the overload relay
The current setting dial can be accessed once
the transparent, sealable cover has been
opened. The overload relay must be set at the
rated full-load amps (FLA) of the motor.
Pressing the red STOP button on the overload
relay momentarily opens the NC trip contact.
No other contacts and/or functions are affect-
ed by this STOP button.
The RESET button/mechanism features trip-
free operation. This means that the overload
relay will trip on an overload condition regard-
less of whether the reset button is pushed in
or not. Manual or automatic reset can be
selected with the blue button. The appropriate
setting is selected by pressing and turning the
button. This setting can then be locked by the
sliding transparent cover.
TEST function and switch
The switch position indicator also incorporates
a test function which, when activated, simu-
lates a tripped overload relay. Both auxiliary
contacts are actuated and the switch position
Terminal for contactor coil and
When the 3RU111 overload relay is mounted
directly on the contactor, the auxiliary contact
terminal and the coil terminal A2 of the con-
tactor are fed through to the bottom side of
the overload relay. This helps considerably in
expediting the wiring for both new and retrofit
applications. The carry through of the A2 coil
1 Equipment identifying marker
2 Manual/automatic RESET selector switch
3 STOP button
4 Complete Catalog No on front of device
5 Switch position indicator and TEST
6 Transparent cover, sealable (secures the cur-
rent setting screw, TEST function and
manual/automatic RESET position)
7 Current setting dial
8 Terminal for contactor coil (when mounted on
9 Terminal for contactor aux. contacts (when
mounted on contactor)
terminal to the bottom of the overload relay is
not necessary with the 3RU112, 3RU113, and
3RU114 devices since the associated contac-
tors are equipped with four point coil connec-
tions and the auxiliary contacts are either front
or side mounted.
Cage Clamp connection
3RU11 overload relays are available with Cage
Clamp terminals. 3RU111 overloads have Cage
Clamps on the auxiliary and power terminals.
3RU112, 3RU113, and 3RU114 overloads, how-
ever, have Cage Clamps on the auxiliary termi-
nals only. The power terminals on 3RU112,
3RU113, and 3RU114 overloads must remain
The accessories available are suitable for use
with all frame sizes.
• Electrically operated remote RESET
available in different voltages
• Plunger type mechanical RESET
for new and existing enclosure
• Flexible cable type RESET mechanism
for applications where the devices are
not easily accessible
The devices are manufactured using environ-
mentally-friendly and recyclable materials only.
IEC 947-1, IEC 947-5-1, and DIN VDE 0660.
3RU11 overload relays are suitable for use in
any climate when used with the correct
The devices are shock-hazard protected to
DIN VDE 0106, Part 100.
UL, CSA, CE marked.
Siemens Energy & Automation, Inc. - SIRIUS 3R IEC Contactors Catalog Supplement 19