Siemens SENTRON 3WA1 - Page 205

Applications
3.2 Using the 3WA circuit breaker for motor protection
3WA1 air circuit breaker
Equipment Manual, 02/2023, 92310000002-06
203
The ETU600 electronic trip unit can be used for motor protection. The protection
parameters are listed in Chapter Setting range for parameter sets A and B (Page 114).
For overload protection, the thermal memory must be activated and the cooling constant
for the simulation of the warming and cooling process must be set to 10 x I
r
. This can be
set using the operating keys on the display or with the help of the SENTRON
powerconfig configuration software via Bluetooth or communication. For protection
parameter set A, the setting is made under display menu item 3.1.1 of the ETU600.
A phase failure is detected if phase failure detection is activated. If the current of the
phase with the lowest load is 50% less than the current of the phase with the highest
load, this is interpreted as a phase failure and the setting I
r
is automatically reduced to
80%. If the three phase currents do not differ by more than 50% with respect to each
other, the setting I
r
applies again.
Protective function
Setting range for parameter sets A
and B
Settings with rotary switch only
possible in parameter set A
L: Overload protection LT
Tripping
Can be switched on/off
Current setting I
r
0.4 ... 1.0 x I
n
0.5 / 0.6 / 0.7 / 0.75 / 0.8 / 0.85 / 0.9
/ 0.95 / 1.0 x I
n
Tripping time t
r
at 6 x I
r
At I
2
t: 0.5 ... 30 s
At I
4
t: 0.5 … 5 s
1 / 2 / 5 / 8 / 10 / 14 / 17 / 21 / 25 s
Characteristic LT curve
I²t / I
4
t
Thermal memory
Can be switched on/off
Cooling time constant
10 / 18 x t
r
Phase failure detection
Can be switched on/off
In addition to the phase failure detection mentioned above, the enhanced protective
function phase current unbalance, see Chapter Enhanced protective functions EPF
(Page 67), also offers protection with an unbalanced load. The setting is made under
display menu item 3.5.5.1 of the ETU600.