Siemens 3RB22 Equipment Manual page 29

2 Device description
Overload
protection
Thermistor
protection
Ground fault
3 Installation
3ZX1012-0RB22-1AA1
The electronic overload relay, consisting of the 3RB22/23
evaluation module and a 3RB29.. current measurement module,
protects electric equipment (e.g. 3-phase motors) using two
different protective mechanisms. Feeder ground fault detection is
also available as an option.
The relay compares the momentary motor current flowing through
the current measurement module with the set value, processes
these values in a microcontroller and releases if necessary.
PTCs (thermistors) in the motor winding measure the motor
temperature. If the temperature specified by the thermistor is
exceeded, the relay will trip. The thermistors are monitored for
short-circuits and line breaks (wire breaks).
The relay can optionally be configured for internal ground fault
detection by the 3RB2985-2..1 function expansion module for use
with motors with a 3-wire connection (without neutral connection).
For the dimension drawing, see graphic section
Mounting position: any
Mounting:
Snap-on mounting to 35 mm standard mounting rail acc. to
7
DIN EN 60715 (Fig. II), or to 3RB2906.. current
measurement module or
Screw mounting with push-in lugs as accessory (3RP1903,
7
).
Fig. III
Device description
Fig. I
19