Siemens SIRIUS System Manual

3RU11, 3RB10, and 3RB12 overload relays
SIRIUS System Manual
4-12
GWA 4NEB 430 0999-02b
Varian ts
The 3RB12 electronic overload relays are available in the following variants:
• Output relay with monostable behavior
• Output relay with bistable behavior
• For the following control supply voltages: 24 VDC
110VAC to 120VAC
220VAC to 240VAC
Auxiliary contact ele-
ments
The 3RB12 electronic overload relays have electrically isolated auxiliary con-
tact elements with the following functions (depending on the variant):
• 1 NO contact/1 NC contact for overload tripping through current and/or
thermistor
1 NO contact/1 NC contact for ground fault tripping
• 1 NO contact/1 NC contact for overload tripping through current and/or
thermistor and ground fault; 1 NO contact/1 NC contact for overload
warning
Overload protection
The currently flowing motor current is detected in each motor supply line by
current transformers and constantly monitored by a microprocessor.
An overload warning occurs as of:
•1.15 x
I
e
in the case of a symmetric load
•0.85 x
I
e
in the case of an asymmetric load
The overload warning is indicated by the flashing "Overload" LED on the
overload relay or externally by means of 1 NO contact/1 NC contact.
Thermistor motor pro-
tection
The continuous evaluation of a PTC thermistor detector ensures thermistor
motor protection.
Additional thermistor motor protection (full motor protection) is imple-
mented by connecting a PTC thermistor detector (PTC sensor circuit in the
motor winding). This is important for stator-critical motors, motors with long
starting and braking, and motors with cooling systems problems or with
high ambient temperatures.
No additional equipment is required for evaluation purposes.
Full motor protection is deactivated on delivery by means of a wire jumper.
The monitoring of the thermistor is secure against a wire break. In other
words, tripping occurs in the event of a wire break.
Ground fault protection
Internal ground fault monitoring
The ground fault protection integrated in the overload relay monitors motors
with a three-conductor terminal. Ground faults are detected in the event of
fault currents > 30 % of the set current
I
e
in rated service.
External ground fault monitoring
External ground fault protection is implemented by connecting a 3UL220.-.A
summation current transformer and monitors motors with three- and four-
conductor terminals. Ground faults are detected reliably in the event of fault
currents of 0.3 A, 0.5 A and 1 A. These values refer to sinusoidal fault cur-
rents 50/60 Hz.

Siemens SIRIUS Specifications

General

Product brand name	Siemens
Series	SIRIUS
Coil Voltage	24V DC, 110V AC, 230V AC
Switching Capacity	Up to 10A
Mounting Type	DIN rail
Product designation	SIRIUS
Contact Material	Silver alloy
Contact Rating	Varies depending on the specific SIRIUS relay model (e.g., 6 A at 250 V AC, 10 A at 250 V AC)
Switching Voltage	Varies depending on the specific SIRIUS relay model (e.g., 250 V AC, 400 V AC)
Mechanical Life	Up to 10 million operations
Electrical Life	Up to 100, 000 operations
Operating Temperature	-25°C to +55°C
Protection Class	IP20
Size of relay base	Varies depending on the specific SIRIUS relay model