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Diagnostics Optimization CT MODBUS RTU Technical Data
122 Installation and System Design Guide
Issue Number: 1
Figure 4-44 Surge suppression for analog bipolar inputs and outputs
Surge suppression devices are available as rail-mounting modules, e.g. from Phoenix Contact:
Unipolar TT-UKK5-D/24 DC
Bipolar TT-UKK5-D/24 AC
These devices are not suitable for encoder signals or fast digital data networks because the capacitance of the diodes adversely affects the signal.
Most encoders have galvanic isolation of the signal circuit from the motor frame, in which case no precautions are required. For data networks, follow
the specific recommendations for the particular network.
4.18 Safe Torque Off (STO)
The E300 Elevator drive has a single channel Safe Torque Off (STO)
4.18.1 Single channel Safe Torque Off (STO)
The Safe Torque Off function provides a means for preventing the drive from generating torque in the motor, with a very high level of integrity. It is
suitable for incorporation into a safety system for a machine. It is also suitable for use as a conventional drive enable input.
The safety function is active when the STO input is in the logic-low state as specified in the control terminal specification. The function is defined
according to EN 61800-5-2 and IEC 61800-5-2 as follows. (In these standards a drive offering safety-related functions is referred to as a PDS (SR)):
'Power that can cause rotation (or motion in the case of a linear motor) is not applied to the motor. The PDS(SR) will not provide energy to the motor
which can generate torque (or force in the case of a linear motor)'.
This safety function corresponds to an uncontrolled stop in accordance with stop category 0 of IEC 60204-1.
The Safe Torque Off function makes use of the special property of an inverter drive with an induction motor, which is that torque cannot be generated
without the continuous correct active behaviour of the inverter circuit. All credible faults in the inverter power circuit cause a loss of torque generation.
The Safe Torque Off function is fail-safe, so when the Safe Torque Off input is disconnected the drive will not operate the motor, even if a combination
of components within the drive has failed. Most component failures are revealed by the drive failing to operate. Safe Torque Off is also independent of
the drive firmware. This meets the requirements of the following standards, for the prevention of operation of the motor.
Machinery Applications
The Safe Torque FUNCTION has been independently assessed by Notified Body, TüV Rheinland for use as a safety component of a machine:
Prevention of unintended motor operation: The safety function "Safe Torque Off" can be used in applications up to Cat 4. PL e according to EN
ISO 13849-1, SIL 3 according to EN 61800-5-2/ EN 62061/ IEC 61508 and in lift applications according to EN 81-1 and EN 81-2.
This certificate is available for download from the TüV Rheinland website
at: http://www.tuv.com.
Safety Parameters as verified by TüV Rheinland:
According to IEC 61508-1 to 07 / EN 61800-5-2 /EN 62061
According to EN ISO 13849-1
Logic levels comply with IEC 61131-2:2007 for type 1 digital inputs rated
at 24 V. Maximum level for logic low to achieve SIL3 and PL e 5 V and
0.5 mA.
Lift (Elevator) Applications
The Safe Torque Off function has been independently assessed for use
as a safety component in lift (elevator) applications by Notified Body,
TüV Nord:
The Unidrive E300 with Safe Torque Off (STO) function if applied
according to the "Conditions of application" fulfil the safety requirements
of the standards EN81-20, EN81-50 and EN60664-1 and are in
conformity with all relevant requirements of the Directive 95/16/EC.
Signal from plant Signal to drive
0V 0V
2 x 15V zener diode
e.g. 2xBZW50-15
Type examination
certificate number
Date of issue Model
01.205/5270.01/14 2014-11-11 E300
Value
Percentage of SIL 3
allowance
Proof test
interval
20 years
High demand or a continuous mode of operation
PFH (1/h)
4.21 x 10
-11
1/h
< 1 %
Low demand mode of operation (not EN61800-5-2)
PFDavg
3.68 x 10
-6
< 1 %
Value Classification
Category 4
Performance Level (PL) e
MTTF
D
>2500 years HIGH
DC
avg
99 % HIGH
Mission time 20 years
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