Flying Restart Without Encoder - Siemens SINAMICS G150 Operating Instructions Manual

Functions, monitoring, and protective functions
9.2 Drive functions
Two different situations are possible here:
1. The drive rotates as a result of external influences, such as water (pump drives) or air
(fan drives). In this case, the drive can also rotate against the direction of rotation.
2. The drive rotates as a result of a previous shutdown (e.g. OFF 2 or a power failure). The
drive slowly coasts to a standstill as a result of the kinetic energy stored in the drive train
(example: induced-draft fan with a high moment of inertia and a steeply descending load
characteristic in the lower speed range).
In accordance with the setting chosen (p1200), the flying restart function is activated in the
following situations:
● Once power has been restored and the automatic restart function is active
● After a shutdown with the OFF2 command (pulse inhibit) when the automatic restart
function is active
● When the ON command is issued.
Note
Applications for flying restart function
The flying restart function must be used when the motor may still be running or is being
driven by the load to prevent shutdowns due to overcurrent (F7801).
Note
Information on flying restart function
If the value set for parameter p1203 (search speed factor) is higher, the search curve is
flatter and, as a result, the search time is longer. A lower value has the opposite effect.
In motors with a low moment of inertia, the flying restart function can cause the drive to
accelerate slightly.
In group drives, the flying restart function should not be activated due to the different
coasting properties of the individual motors.
9.2.6.1

Flying restart without encoder

Description
Depending on parameter p1200, the flying restart function is started with the maximum
search speed n
"Flying restart").
n
Search,max
The flying restart function behaves differently with V/f control and vector control:
● V/f characteristic (p1300 < 20):
The search speed yielded from parameter p1203 reduces the search frequency in
accordance with the motor current. The parameterizable search current (p1202) is
injected here. If the search frequency is similar to the rotor frequency, a current minimum
496
once the de-excitation time (p0347) has elapsed (see diagram
search,max
= 1.25 x n (p1082)
max
Converter cabinet units
Operating Instructions, 07/2016, A5E03347396A