NOTICE
The discrepancy time does not extend the safety option
response time. The safety option activates its safety
function as soon as one of the 2 DI signals changes from
high to low.
3.6.7 Stable Signal Time from Safe Outputs
The safety option normally responds immediately to signal
changes at its safe input DI1 or DI2. This response is not
required in the following cases
•
When interconnecting the safe input of the
option with an electromechanical sensor, contact
bounce may result in signal changes occurring, to
which the option could respond.
•
Several control modules test their safe outputs
using test pulse pattern (on/off tests), to identify
faults due to either short or cross circuiting.
When interconnecting the safe input of the
option with a safe output of a control module,
the option could respond to these test signals.
A signal change during a test pulse pattern usually lasts 1
ms.
Under stable signal time, short pulses, which could lead to
safety functions being incorrectly activated, can be filtered.
NOTICE
The stable signal time extends the safety option
response time. The safety option only activates the
safety function after the response time has expired.
If the signal to the input on safety option is not stable, the
option responds with a fault.
Definition of a stable signal
Following a change to the DI input signals, the option
triggers an internal monitoring time. Use
42-23 Stable
Signal Time
to select an appropriate stable signal time. A
constant signal level is a high or a low state, for at least
42-23 Stable Signal Time
.
Input Signal
130BC317.10
DI1/DI2
Safety function
Active
Inactive
Test pulse pattern
Stable signal time
Stable signal time
Illustration 3.15 Filter for Suppressing Temporary Signal
Changes
3.6.8 Zero Speed Time Error Detection
Zero Speed Timer monitors if the frequency converter is
operated below 120 RPM during Safely Limited Speed.
42-18 Zero Speed Timer
contains the remaining time until
the monitoring responds. The safety option signals
Alarm
Ext Fail Prec Thresh Timer Elapsed
after the monitoring time
expires.
Define the monitoring time while commissioning the
system depending on the particular application.
3.6.9 Yearly Test
According to EN ISO 13849-1, EN IEC 62061 and EN IEC
61508, the safety option must regularly test its safety-
relevant circuits to ensure correct functioning. This test
must be performed at least once every year. After the
power supply has been connected, the safety option
checks its circuits to switch-off the torque each time the
Safe Torque Off function is selected. The safety option
monitors the regular test interval of its safety-relevant
circuits using a time module.
After one year in operation, the frequency converter
displays a message that a yearly test must be performed.
The frequency converter must be power cycled by discon-
necting and then reconnecting the supply voltage. Activate
the used inputs on the safety option and check that they
function correctly.
3.6.10 Safety Parameter Settings
Factory setting for both digital inputs is Safe Torque Off,
meaning that the Safe Output S37 is in low state.
Functions and System Overvi...
Operating Instructions
MG34W302
Danfoss A/S © Rev. 2014-02-11 All rights reserved.
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