Overload Relays 3RB2 Solid-State Overload Relays 3RB22, 3RB23 for high-feature applications Function The 3RB22/3RB23 solid-state overload relays are designed for:
Inverse-time delayed protection of loads from overloading Inverse-time delayed protection of loads from phase unbalance Inverse-time delayed protection of loads from phase failure Temperature-dependent protection of loads by connecting a PTC sensor circuit Protection of loads from high-resistance short-circuits (internal ground-fault detection; detection of fault currents > 30 % of the current setting I e ) Output of an overload warning Output of an analog signal 4 to 20 mA DC as image of the flow- ing motor current Basic functions Trip classes The 3RB22/3RB23 solid-state overload relays are suitable for normal and heavy starting conditions.
The required trip class (CLASS 5, 10, 20 or 30) can be adjusted by means of a rotary switch depending on the current start-up condition. For details of the trip classes see "Characteristic Curves" . Phase failure protection The 3RB22/3RB23 solid-state overload relays are fitted with phase failure protection (see "Characteristic Curves") in order to minimize temperature rises of the load during single-phase ope- ration. Setting The 3RB22/3RB23 solid-state overload relays are set to the rated motor current by means of two rotary knobs. The upper rotary knob (CLASS/ I emax ) is divided into 4 ranges: 1 A, 10 A, 100 A and 1000 A.
The zone must be selected which corresponds to the rated motor current and the current measuring module to be used with it. With the range selected the required trip class (CLASS 5, 10, 20 or 30) can be deter- mined. The lower rotary knob with percent scale (10 ... 100 %) is then used to set the rated motor current in percent of the range se- lected with the upper rotary knob. The basic functions of the evaluation modules in conjunction with function expansion modules are listed in the following table: Example Rating of induction motor = 45 kW (AC 50 Hz, 400 V) Rated motor current = 80 A Required trip class = CLASS 20 Selected transformer: 10 ... 100 A Solution Step 1:
Use the upper rotary knob (CLASS) to select the 100 A range Step 2: Within the 100 A range set the trip class CLASS 20 Step 3: Set the lower rotary knob to 80 % (= 0.8) correspon- ding to 100 A Ч 0.8 = 80 A. If the current which is set on the evaluation module does not cor- respond to the current range of the connected current transfor- mer, an error will result. Manual and automatic reset In the case of the 3RB22/3RB23 solid-state overload relays, a slide switch can be used to choose between automatic and ma- nual resetting. Control circuit If manual reset is set, a reset can be carried out directly on the device after a trip by pressing the blue TEST/RESET button.
A re- mote RESET can be carried out electrically by jumpering the ter- minals Y1 and Y2. The 3RB22/3RB23 solid-state overload relays require an exter- nal power supply, i. e. an additional supply voltage is necessary. Power is supplied through a wide-range power supply unit for 24 to 240 V AC/DC. If the slide switch is set to automatic RESET, the relay is reset au- tomatically. Short-circuit protection Fuses or motor starter protectors must be used for short-circuit protection. The time between tripping and resetting is determined by the re- covery time.
For assignments of the corresponding short-circuit protection devices to the 3RB22/3RB23 solid-state overload relays with/without contactor see "Technical specifications" and Catalog LV 1, "Selection and ordering data" .
31 Siemens · 2009 Evaluation modules Function expan- sion modules Basic functions 3RB22 83-4AA1 3RB22 83-4AC1 3RB23 83-4AA1 3RB23 83-4AC1 None Inverse-time delayed protection, temperature-dependent protection, electrical remote RESET, overload warning 3RB29 85-2CA1 Inverse-time delayed protection, temperature-dependent protection, internal ground-fault detection, electrical remote RESET, overload warning 3RB29 85-2CB1 Inverse-time delayed protection, temperature-dependent protection, internal ground-fault detection, electrical remote RESET, ground-fault signal 3RB29 85-2AA0 Inverse-time delayed protection, temperature-dependent protection, electrical remote RESET, overload warning, analog output 3RB29 85-2AA1 Inverse-time delayed protection, temperature-dependent protection, internal ground-fault detection, electrical remote RESET, overload warning, analog output 3RB29 85-2AB1 Inverse-time delayed protection, temperature-dependent protection, internal ground-fault detection, electrical remote RESET, ground-fault signal, analog output