SIEMENS
7/74
Siemens IC 10 · 2017
Overload Relays
General data
7
✓
Available
--
Not available
1)
SIRIUS 3RU11 and 3RU21 thermal overload relays use a bimetal contactor
and therefore do not require a control supply voltage.
Features
3RU21
3RB30/3RB31
3RB20/3RB21
3RB22/3RB23
3RB24
Benefits
Other features
Temperature
compensation
✓
✓
✓
✓
✓
• Allows the use of the relays at high
temperatures without derating
• Prevents premature tripping
• Allows compact installation of the control
cabinet without distance between the
devices/load feeders
• Simplifies configuration
• Enables space to be saved in the control
cabinet
Very high long-term
stability
✓
✓
✓
✓
✓
• Provides safe protection for the loads even
after years of use in severe operating
conditions
Wide setting ranges
--
✓
(1:4)
✓
(1:4)
✓
(1:10)
✓
(1:10)
• Minimize the configuration outlay and costs
•
Minimize storage overheads, storage costs,
tied-up capital
Fixed trip class
CLASS 10,
CLASS 10A
3RB30:
CLASS 10E or
CLASS 20E
3RB20:
CLASS 10E or
CLASS 20E
--
--
• Optimum motor protection for standard
starts
Trip classes
adjustable on the
device CLASS 5E,
10E, 20E, 30E
--
3RB31:
✓
3RB21:
✓
✓
✓
• Enables solutions for very fast starting
motors requiring special protection
(e.g. Ex motors)
• Enables heavy starting solutions
• Reduces the number of variants
• Minimizes the configuring outlay and costs
•
Minimizes storage overhead, storage costs,
and tied-up capital
Low power loss
--
✓
✓
✓
✓
• Reduces power consumption and energy
costs (up to 98 % less power is used than
for thermal overload relays)
• Minimizes temperature rises of the
contactor and control cabinet – in some
cases this may eliminate the need for
control cabinet cooling.
• Direct mounting to contactor saves space,
even for high motor currents (i.e. no heat
decoupling is required)
Internal power
supply
--
1)
✓
✓
--
--
• Eliminates the need for configuration and
connecting an additional control circuit
Supplied from an
external source via
IO-Link
--
--
--
--
✓
• Eliminates the need for configuration and
connecting an additional control circuit
© Siemens AG 2016