Bypass - Siemens SINAMICS S120 Function Manual

Vector control

4.22 Bypass

4.22 Bypass
Features
● Available for the vector mode
● Available for induction motors without encoder
Description
The bypass function controls two contactors via digital outputs of the drive converter and
evaluates the feedback signals of the contactors via digital inputs (e.g. via TM31). This circuit
allows the motor to either be fed from the drive converter or connected directly to the supply
line. The drive converter controls the contactors; the feedback signals for the contactor
states must be fed back to the drive converter.
This bypass circuit can be implemented in two ways:
● Without synchronizing the motor to the line supply and
● Synchronizing the motor to the line supply.
For all bypass versions, the following applies:
● The bypass is always switched-out when one of the control word signals "OFF2" or
● Exception:
● When the drive converter restarts after POWER OFF, the state of the bypass contactors
● Changing the converter into "Ready to start and bypass" status after powering up, is of a
● Monitoring of the motor temperatures using temperature sensors is active while the
● The two motor contactors must be designed for switching under load.
Note
The examples contained in the following descriptions are only basic circuits designed to
explain the basic function. The dimensions of specific circuit configurations (contactors,
protective equipment) must be calculated for specific systems.
Prerequisite
The bypass function is only possible for encoderless closed-loop speed control (p1300 = 20)
or V/f control (p1300 = 0...19) and when an induction motor is used.
174
"OFF3" is withdrawn.
When required, the bypass switch can be interlocked by a higher-level control so that the
drive converter can be completely powered-down (i.e. including the control electronics)
while the motor is operated from the line supply. The contactor interlocking should be
implemented on the plant/system side.
is evaluated. After powering up, the converter can thereby change straight into "Ready to
start and bypass" status. This is only possible if the bypass is activated via a control
signal, the control signal (p1266) is still present once the system has been ramped up,
and the automatic restart function (p1200 = 4) is active.
higher priority than switching back on automatically.
converter is in one of two statuses "Ready to start and bypass" or "Ready to operate and
bypass".
Function Manual, (FH1), 10/2008, 6SL3097-2AB00-0BP5
Drive functions