Functions, monitoring, and protective functions
9.4 Extended functions
Drive converter cabinet units
Operating Instructions, 07/07, A5E00288214A
341
9.4.2
Bypass function
The bypass function uses digital converter outputs to activate two contactors and uses digital
inputs to evaluate the contactor’s feedback (e.g. via TM31). This circuit allows the motor to
be operated using the converter or directly on the supply line. The contactors are activated
by the converter. The feedback signals for the contactor positions have to be returned to the
converter.
The bypass circuit can be implemented in two ways:
●
without synchronizing the motor to the supply and
●
with synchronizing the motor to the supply.
The following applies to all bypass versions:
●
The bypass switch is also shut down when one of the "OFF2" or "OFF3" control word
signals is canceled.
●
Exception:
If necessary, the bypass switch can be interlocked by a higher-level controller such that
the converter can be shut down completely (i.e. including the controller electronics) while
the motor is operated on the supply.
The protective interlocking must be implemented on the system side.
●
When the converter is started up again after POWER OFF, the status of the bypass
contactors 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.
●
Changing the converter into "Ready to start and bypass" status after powering up, is of a
higher priority than switching back on automatically.
●
Monitoring of the motor temperatures using temperature sensors is active while the
converter is in one of two statuses "Ready to start and bypass" or "Ready to operate and
bypass".
●
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.
Prerequisites
The bypass function is only available for sped control without encoders (p1300 = 20) or V/f-
control (p1300 = 0...19) and when using an asynchronous motor.
Establishing the bypass function
The bypass function is part of the "technology controller" function module that can be
activated by running the commissioning Wizard. Parameter r0108.16 indicates whether the
function module has been activated.