Specifications

Safe Torque Off Installation and Set-Up
WARNING
SAFE TORQUE OFF FUNCTION!
The Safe Torque Off function does NOT isolate mains
voltage to the frequency converter or auxiliary circuits.
Perform work on electrical parts of the frequency
converter or the motor only after isolating the mains
voltage supply and waiting the length of time specified
under Safety in this manual. Failure to isolate the mains
voltage supply from the unit and waiting the time
specified could result in death or serious injury.
•
It is not recommended to stop the frequency
converter by using the Safe Torque Off function.
If a running frequency converter is stopped by
using the function, the unit trips and stops by
coasting. If this is not acceptable, e.g. causes
danger, the frequency converter and machinery
must be stopped using the appropriate stopping
mode before using this function. Depending on
the application a mechanical brake may be
required.
•
Concerning synchronous and permanent magnet
motor frequency converters in case of a multiple
IGBT power semiconductor failure: In spite of the
activation of the Safe Torque Off function, the
frequency converter system can produce an
alignment torque which maximally rotates the
motor shaft by 180/p degrees. p denotes the pole
pair number.
•
This function is suitable for performing
mechanical work on the frequency converter
system or affected area of a machine only. It does
not provide electrical safety. This function should
not be used as a control for starting and/or
stopping the frequency converter.
Meet the following requirements to perform a safe instal-
lation of the frequency converter:
1. Remove the jumper wire between control
terminals 37 and 12 or 13. Cutting or breaking
the jumper is not sufficient to avoid short-
circuiting. (See jumper on Illustration 2.1.)
2. Connect an external Safety monitoring relay via a
NO safety function (the instruction for the safety
device must be followed) to terminal 37 (Safe
Torque Off) and either terminal 12 or 13 (24 V
DC). The Safety monitoring relay must comply
with Category 3/PL “d” (ISO 13849-1) or SIL 2 (EN
62061).
12/13
37
130BA874.10
Illustration 2.1 Jumper between Terminal 12/13 (24 V) and 37
12
37
3
2
FC
4
1
130BB967.10
Illustration 2.2 Installation to Achieve a Stopping Category 0
(EN 60204-1) with Safety Cat. 3/PL “d” (ISO 13849-1) or SIL 2
(EN 62061).
1 Safety relay (cat. 3, PL d or SIL2
2 Emergency stop button
3 Reset button
4 Short-circuit protected cable (if not inside installation IP54
cabinet)
Table 2.3 Legend to Illustration 2.2
Safe Torque Off Commissioning Test
After installation and before first operation, perform a
commissioning test of the installation making use of Safe
Torque Off. Moreover, perform the test after each modifi-
cation of the installation.
Example with STO
A safety relay evaluates the E-Stop button signals and
triggers an STO function on the frequency converter in the
event of an activation of the E-Stop button (See
Illustration 2.3). This safety function corresponds to a
category 0 stop (uncontrolled stop) in accordance with IEC
60204-1. If the function is triggered during operation, the
motor runs down in an uncontrolled manner. The power
Introduction to VLT® HVAC D...
Design Guide
16 Danfoss A/S © Rev. 06/2014 All rights reserved. MG11BC02
22