Mode Of Operation Of The Start Inhibit - Siemens SIMODRIVE 611 Planning Manual

05.01
9.5.2

Mode of operation of the start inhibit

The inverter power module controls the current through the individual motor
windings. 1FT5 motors are fed with square–wave current.
A pulse generating logic clocks the 6 power transistors in a three–phase orien-
ted pulse pattern An optocoupler is provided in every transistor arm between
the gating logic and the power section gating amplifier. These optocouplers pro-
vide the electrical isolation.
The start inhibit acts on each module. A positively–driven relay (permitted ac-
cording to ZH1/457, TÜV) acts on the inverter gating on the particular drive mo-
dule at the input circuits of the optocouplers.
A relay contact interrupts the power supply for the optocoupler inputs. Thus, no
signals can be transferred through the optocoupler. The pulse generating logic
is inhibited through an additional electrically isolated arm.
These two active circuits are controlled in parallel from the machine control via
terminal 663 (motor start inhibit) for the drive modules or via terminal 112 (DC
link controller start inhibit) for the line supply infeed modules.The status of the
relay contact, located in the pulse power supply circuit, is signaled to the exter-
nal adaptation circuit via a positively–driven NC contact.
The signaling contact is accessible at module terminals AS1 and AS2, and the
user can interlock it with the safety control. When the start inhibit fails, these
start–inhibit signaling contacts must isolate the supply infeed from the supply
via the power contactor (line contactor in the supply module).
If the start inhibit circuit is activated, it is no longer possible to control the power
transistors in a rotating field. When two power transistors are destroyed (double
fault) in the most unfavorable constellation, then this results in the residual risk
as described in Section 9.5.1.
Warning
!
When the start inhibit is activated, the motor can no longer generate a torque.
Drives which are not automatically clamped when powered down (e.g. vertical/
inclined axes), must be clamped using a mechanical brake.
9.5.3 Connecting the start inhibit
The start inhibit function is controlled in the drive modules using terminal 663 or
in the infeed modules using terminal 112. The start inhibit relay is controlled
using the internal/external +24 V enable voltage (FR+ terminal 9; FR– terminal
19).
When the relay is de–energized, terminal 663 is open–circuit, the start inhibit is
activated.
The AS1/AS2 signal contact closed indicates the condition "start inhibit" is effec-
tive. The circuit must be protected against overload and short–circuit using a
fuse of max. 2 A!
Terminal 663 (drive) and terminal 112 (NE–module) must be externally control-
led using a fail–safe signal.
 Siemens AG 2001 All rights reserved
SIMODRIVE 611 Planning Guide (PJU) – 05.01 Edition
9 Important Circuit Information
9.5 Start inhibit in the drive modules
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