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Overload Relays
3RB2 Solid-State Overload Relays
3RB22, 3RB23 for high-feature applications
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Function
Basic functions
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
The basic functions of the evaluation modules in conjunction with
function expansion modules are listed in the following table:
Evaluation
Function expan-
modules
sion modules
3RB22 83-4AA1
None
3RB22 83-4AC1
3RB23 83-4AA1
3RB23 83-4AC1
3RB29 85-2CA1
3RB29 85-2CB1
3RB29 85-2AA0
3RB29 85-2AA1
3RB29 85-2AB1
Control circuit
The 3RB22/3RB23 solid-state overload relays require an external
power supply, i. e. an additional supply voltage is necessary. Po-
wer is supplied through a wide-range power supply unit for 24 to
240 V AC/DC.
Short-circuit protection
Fuses or motor starter protectors must be used for short-circuit
protection.
For assignments of the corresponding short-circuit protection de-
vices to the 3RB22/3RB23 solid-state overload relays with/without
contactor see "Technical specifications" and
Catalog LV 1, "Selection and ordering
30
Siemens · 2011
Basic functions
Inverse-time delayed protection,
temperature-dependent protection,
electrical remote RESET,
overload warning
Inverse-time delayed protection,
temperature-dependent protection,
internal ground-fault detection,
electrical remote RESET,
overload warning
Inverse-time delayed protection,
temperature-dependent protection,
internal ground-fault detection,
electrical remote RESET,
ground-fault signal
Inverse-time delayed protection,
temperature-dependent protection,
electrical remote RESET,
overload warning,
analog output
Inverse-time delayed protection,
temperature-dependent protection,
internal ground-fault detection,
electrical remote RESET,
overload warning,
analog output
Inverse-time delayed protection,
temperature-dependent protection,
internal ground-fault detection,
electrical remote RESET,
ground-fault signal,
analog output
data".
Trip classes
The 3RB22/3RB23 solid-state overload relays are suitable for nor-
mal 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
Phase failure protection
The 3RB22/3RB23 solid-state overload relays are fitted with phase
failure protection
(see "Characteristic Curves")
mize temperature rises of the load during single-phase operation.
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
1 A, 10 A, 100 A and 1000 A. The zone must be selected which
corresponds to the rated motor current and the current measu-
ring module to be used with it. With the range selected the re-
quired trip class (CLASS 5, 10, 20 or 30) can be determined.
• 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.
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) corresponding
to 100 A × 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.
If manual reset is set, a reset can be carried out directly on the de-
vice after a trip by pressing the blue TEST/RESET button. A remote
RESET can be carried out electrically by jumpering the terminals
Y1 and Y2.
If the slide switch is set to automatic RESET, the relay is reset au-
tomatically.
The time between tripping and resetting is determined by the re-
covery time.
Curves".
in order to mini-
) is divided into 4 ranges:
emax
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