SIEMENS
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Siemens IC 10 · 2017
Overload Relays
SIRIUS 3RB2 Electronic Overload Relays
3RB20, 3RB21 for standard applications
7
Article No. scheme
Note:
The Article No. scheme shows an overview of product versions
for better understanding of the logic behind the article numbers.
For your orders please use the article numbers quoted in the
selection and ordering data.
■
Benefits
The most important features and benefits of the 3RB20/3RB21
electronic overload relays are listed in the overview table
(see "General Data", page 7/71 onwards)
■
Application
Industries
The 3RB20 and 3RB21 electronic overload relays are suitable for
customers from all industries who want to guarantee optimum
inverse-time delayed protection of their electrical loads
(e.g. motors) under normal and heavy starting conditions
(CLASS 5E to 30E), minimize project completion times, invento-
ries and energy consumption, and optimize plant availability and
maintenance management.
Application
The 3RB20 and 3RB21 electronic overload relays have been
designed for the protection of three-phase motors in sinusoidal
50/60 Hz voltage networks. The relays are not suitable for the
protection of single-phase AC or DC loads.
The 3RU21 thermal overload relays or the 3RB22 to 3RB24 elec-
tronic overload relays can be used for single-phase AC loads.
For DC loads we recommend the 3RU21 thermal overload relay.
Ambient conditions
The devices are insensitive to external influences such as
shocks, corrosive ambient conditions, ageing and temperature
fluctuations.
For the temperature range from –25 C to +60 °C, the 3RB20 and
3RB21 electronic overload relays compensate the temperature
in accordance with IEC 60947-4-1.
For the 3RB20 and 3RB21 electronic overload relays with the
sizes S6, S10 and S12, the upper set value of the setting range
must be reduced for ambient temperatures > 50 °C by a certain
factor.
Use of SIRIUS protection devices in conjunction with
IE3/IE4 motors
Note:
For the use of 3RB20 and 3RB21 electronic overload relays in
conjunction with highly energy-efficient IE3/IE4 motors, please
observe the information on dimensioning and configuring,
see
Application Manual
.
For more information,
see Preface on page 7.
Product versions
Article number
Electronic overload relays
3RB2
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Device type
e. g. 0 = standard device, with internal
supply, for three-phase loads
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Size, rated operational current and
power
e. g. 5 = 200 A (90 kW) for size S6
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Version of the automatic RESET,
electrical remote RESET
e. g. 6 = switchable between manual/auto
RESET
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Trip class (CLASS)
e. g. 1 = CLASS 10E
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Setting range of the overload release
e.g. F = 5 ... 200 A
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Connection methods
e.g. C = busbar connections main circuit;
screw terminals auxiliary circuit
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Installation type
e. g. 2 = mounting on contactor and
stand-alone installation
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Example
3RB2
0
5
6
–
1
F
C
2
© Siemens AG 2016