Safe Torque Off (Sto) - Kollmorgen AKD Serie Manual De Instrucciones

AKD Product Safety Guide | 1 English

1.5.7 Safe Torque Off (STO)

The STO safety implementation on the AKD 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
62061 and PLd / CAT3 according to ISO 13849-1. SIL3/PLe is possible with AKD-x04807
drives, if both STO-Enable inputs and the corresponding STO-Status signals are used.
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.
1.5.7.1 Important Notes
Serious injury could result when a suspended load is not properly blocked. The drive cannot
hold a vertical load when STO is active.
Risk of electrical shock! The STO function does not provide an electrical separation from the
power output. If access to the motor power terminals is necessary,
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. The monitoring can be
used to prevent a faulty output from unintentionally activating the STO function. Since the
STO function is a single-channel system, erroneous engaging will not be recognized.
It is not possible to perform a controlled brake if the drive controlled STO-Enable is off. If con-
trolled braking before the use of the STO function is necessary, the drive must be braked
and the input STO must be separated time-delayed from +24 V .
In case of a specific double fault within a very short time a single movement of a maximum
angle of 120° (electrical) can happen. This effect can only happen if the drive is in the func-
tion STO. Even if the STO function will be issued for a whole year, this event will only hap-
pen every 100 Billion years.
Use the following functional sequence when the STO function is used:
1. Brake the drive in a controlled manner (speed setpoint = 0 V).
2. When speed = 0 rpm, disable the drive (enable = 0 V).
3. If a suspended load is present, block the drive mechanically.
4. Activate the STO function.
18 Kollmorgen | kdn.kollmorgen.com | October 2018
AKD-x003 up to AKD-x024: 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.
AKD-x048: Two additional digital inputs (STO-Enable 1 and STO-Enable 2) release the
power output stage of the drive as long as a 24 V signal is applied to these inputs.
WARNING
No Brake Power!
Add a safe mechanical blocking (for instance, a motor-holding brake).
CAUTION
High electrical voltage!
disconnect the drive from mains supply,
consider the discharging time of the DC-Bus link.