12
37
FC
20
130BC001.10
FC
FC
20
20
37
37
3
1
2
4
Illustration 2.6 Paralleling of Multiple Frequency Converters
Example
1
Safety relay
2
Emergency stop button
3
Reset button
4
24 V DC
Table 2.4 Legend to
to
WARNING
Safe Torque Off activation (i.e. removal of 24 V DC
voltage supply to terminal 37) does not provide
electrical safety. The Safe Torque Off function itself is
therefore not sufficient to implement the Emergency-Off
function as defined by EN 60204-1. Emergency-Off
requires measures of electrical isolation, e.g. by
switching off mains via an additional contactor.
1.
Activate the Safe Torque Off function by
removing the 24 V DC voltage supply to the
terminal 37.
2.
After activation of Safe Torque Off (i.e. after the
response time), the frequency converter coasts
(stops creating a rotational field in the motor).
The response time is typically shorter than 10 ms
for the complete performance range of the
frequency converter.
The frequency converter is guaranteed not to restart
creation of a rotational field by an internal fault (in
accordance with Cat. 3 PL d acc. EN ISO 13849-1 and SIL 2
acc. EN 62061). After activation of Safe Torque Off, the
frequency converter display shows the text Safe Torque Off
activated. The associated help text says "Safe Torque Off
has been activated. This means that the Safe Torque Off
has been activated, or that normal operation has not been
resumed yet after Safe Torque Off activation.
NOTICE
The requirements of Cat. 3/PL “d” (ISO 13849-1) are only
fulfilled while 24 V DC supply to terminal 37 is kept
removed or low by a safety device, which itself fulfills
Cat. 3/PL “d” (ISO 13849-1). If external forces act on the
motor e.g. in case of vertical axis (suspended loads) -
and an unwanted movement, for example caused by
gravity, could cause a hazard, the motor must not be
operated without additional measures for fall protection.
E.g. mechanical brakes must be installed additionally.
To resume operation after activation of Safe Torque Off,
first reapply 24 V DC voltage to terminal 37 (text Safe
Torque Off activated is still displayed), second create a
reset signal (via bus, Digital I/O, or [Reset] key on inverter).
By default the Safe Torque Off functions is set to an
Unintended Restart Prevention behaviour. This means, in
order to terminate Safe Torque Off and resume normal
operation, first the 24 V DC must be reapplied to Terminal
37. Subsequently, give a reset signal (via Bus, Digital I/O, or
[Reset] key).
The Safe Torque Off function can be set to an Automatic
Restart Behaviour by setting the value of
5-19 Terminal 37
Safe Stop
from default value [1] to value [3]. If a MCB 112
Option is connected to the frequency converter, then
Automatic Restart Behaviour is set by values [7] and [8].
Automatic Restart means that Safe Torque Off is
terminated, and normal operation is resumed, as soon as
the 24 V DC is applied to Terminal 37, no reset signal is
required.
WARNING
Automatic Restart Behaviour is only allowed in one of
the 2 situations:
1.
The Unintended Restart Prevention is
implemented by other parts of the Safe Torque
Off installation.
2.
A presence in the dangerous zone can be
physically excluded when Safe Torque Off is not
activated. In particular, paragraph 5.3.2.5 of ISO
12100-2 2003 must be observed
2.6.2 Installation of External Safety Device
in Combination with MCB 112
If the Ex-certified thermistor module MCB 112, which uses
Terminal 37 as its safety-related switch-off channel, is
connected, then the output X44/12 of MCB 112 must be
AND-ed with the safety-related sensor (such as emergency
stop button, safety-guard switch, etc.) that activates Safe
Torque Off. This means that the output to Safe Torque Off
terminal 37 is HIGH (24 V) only, if both the signal from
Introduction to VLT® HVAC D...
Design Guide
18
Danfoss A/S © Rev. 06/2014 All rights reserved.
MG11BC02
2
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