Bypass (Vector) - Siemens SINAMICS S120 Function Manual

4.25

Bypass (vector)

Features
S Available for the vector mode
S Available for induction motors without encoder
Description
The bypass function controls two contactors via digital outputs of the drive con-
verter 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 con-
verter.
This bypass circuit can be implemented in two ways:
S Without synchronizing the motor to the line supply and
S Synchronizing the motor to the line supply.
For all bypass versions, the following applies:
S The bypass is always switched-out when one of the control word signals
"OFF2" or "OFF3" is withdrawn.
S Exception:
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.
S When the drive converter restarts after POWER OFF, the state of the bypass
contactors is evaluated. This means that after running-up, the drive converter
can directly change into the standby mode. This is only possible if the bypass is
activated using a control signal (p1267.0 = 1, p1267.1 = 0, p1267.2 = 0) and the
control signal (p1266) is still present after the drive has ramped-up.
S A changeover of the drive converter into the standby mode after the drive has
ramped-up has a higher priority than the automatic restart.
S The motor temperatures are monitored using temperature sensors while the
drive converter is only of the two standby modes.
S The two motor contactors must be designed for switching under load.
Requirements
The bypass function is only possible for sensorless close-loop speed control
(p1300 = 20) or V/f control (p1300 = 0...19) and when an induction motor is used.
A VSM10 must be used for synchronizing with overlap.
© Siemens AG 2006 All Rights Reserved
SINAMICS S120 Function Manual, 03/2006 Edition
Extended Functions
Bypass (vector)
4-277