Safe Torque Off (Sto); Safety Instructions - Kollmorgen SERVOSTAR 300 Manuel D'instructions

S300 Safety Guide | 2 English

2.3.9 Safe Torque Off (STO)

The STO safety implementation on the is certified. The safety circuit implementation used for
the safety function "Safe Torque Off" in the drive is suited for SIL 2 according to IEC 61508-2
and PLd / CAT3 according to ISO 13849-1.
An additional digital input (STO) releases the power output stage of the drive as long as a 24
V signal is applied to this input. If the STO input goes open-circuit, then power will no longer
be supplied to the motor, and the drive will lose all torque and coast to a stop.

2.3.9.1 Safety instructions

WARNING
The drive cannot hold a vertical load when STO function is active. Serious
injury could result when load is not properly blocked. Drives with a sus-
pended load must have an additional safe mechanical blocking (for
instance, by a safe brake).
CAUTION
The STO function does not provide an electrical separation from the
power output. There is a danger of electrical shock and personnel injury! If
access to the motor power terminals is necessary, the drive must be dis-
connected from mains supply considering the discharging time of the inter-
mediate circuit.
If the safety function STO is automatically activated by a control system, then make sure
that the output of the control is monitored for possible malfunction. This can be used to pre-
vent a faulty output from unintentionally activating the safety function STO. Since the restart
lock is a single-channel system, erroneous engaging will not be recognized.
When STO is engaged during operation by separating input STO-Enable from 24VDC, the
motor runs down out of control and the servo amplifier displays the error F27. There is no pos-
sibility of braking the drive controlled. Risk from uncontrolled movement! If a controlled brak-
ing before the use of STO is necessary, the drive must be braked and the input STO-
ENABLE has to be separated from +24 VDC time-delayed.
When wiring the STO input within one enclosure it must be paid attention to the fact that the
used cables and the enclosure meet the requirements of IEC 60204-1. If the wiring leads out-
side the demanded enclosure, the cables must be laid durably (firmly), and protected from out-
side damage.
Keep to the following functional sequence when the restart lock STO is used :
1. Brake the drive in a controlled manner (speed setpoint = 0V)
2. When speed = 0 rpm, disable the servo amplifier (enable = 0V)
3. If there is a suspended load, block the drive mechanically
4. Activate STO
If the STO function is not needed in the application, then the input STO-ENABLE must be
connected directly with +24VDC. The STO function is passed by now and cannot be used.
The servo amplifier cannot be used as a safety component referring to the EC Machine Dir-
ective now.
50 Kollmorgen | June 2015