Requirements for Using the Safety Function
The safety function STO (Safe Torque Off) does not remove power from the DC bus. The safety function STO only removes power to the motor. The DC bus voltage and the mains voltage to the drive are still present.
|
|
|
ELECTRIC SHOCK |
|
oDo not use the safety function STO for any other purposes than its intended function. oUse an appropriate switch, that is not part of the circuit of the safety function STO, to disconnect the drive from the mains power. |
|
Failure to follow these instructions will result in death or serious injury. |
After the safety function STO is triggered, the motor can no longer generate torque and coasts down without braking.
|
|
|
UNINTENDED EQUIPMENT OPERATION |
|
Install a dedicated service brake if coasting does not meet the deceleration requirements of your application. |
|
Failure to follow these instructions can result in death, serious injury, or equipment damage. |
The inputs for the safety function STO (inputs STO_A and STO_B) can only be wired for positive logic.
Holding Brake and Safety Function STO
When the safety function STO is triggered, the power stage is immediately disabled. Applying the holding brake requires a certain amount of time. In the case of vertical axes or external forces acting on the load, you may have to take additional measures to bring the load to a standstill and to keep it at a standstill when the safety function STO is used, for example, by using a service brake.
|
|
|
FALLING LOAD |
|
Ensure that all loads come to a secure standstill when the safety function STO is used. |
|
Failure to follow these instructions can result in death, serious injury, or equipment damage. |
If the suspension of hanging / pulling loads is a safety objective for the machine, then you can only achieve this objective by using an appropriate external brake as a safety-related measure.
|
|
|
UNINTENDED AXIS MOVEMENT |
|
oDo not use the internal holding brake as a safety-related measure. oOnly use certified external brakes as safety-related measures. |
|
Failure to follow these instructions can result in death, serious injury, or equipment damage. |
NOTE: The drive does not provide its own safety-related output to connect an external brake to use as a safety-related measure.
|
|
|
UNINTENDED EQUIPMENT OPERATION |
|
oVerify that your risk assessment covers all potential effects of automatic or unintended enabling of the power stage, for example, after power outage. oImplement all measures such as control functions, guards, or other safety-related functions, required to reliably protect against all hazards that may result from automatic or unintended enabling of the power stage. oVerify that a master controller cannot enable the power stage in an unintended way. |
|
Failure to follow these instructions can result in death, serious injury, or equipment damage. |
Degree of Protection when the Safety Function is Used
You must ensure that conductive substances cannot get into the product (pollution degree 2). Moreover, conductive substances may cause the safety function to become inoperative.
|
|
|
INOPERABLE SAFETY FUNCTION |
|
Ensure that conductive substances (water, contaminated or impregnated oils, metal shavings, etc.) cannot get into the drive. |
|
Failure to follow these instructions can result in death, serious injury, or equipment damage. |
If short circuits and other wiring errors such as a cross fault between the signals of the safety function STO can be expected in connection with safety-related signals, and if these short circuits and cross faults are not detected by upstream devices, protected cable installation as per ISO 13849-2 is required.
In the case of an unprotected cable installation, the two signals (both channels) of a safety function may be connected to external voltage if a cable is damaged. If the two channels are connected to external voltage, the safety function is no longer operative.
ISO 13849-2 describes protected cable installation for cables for safety-related signals. The cables for the safety function STO must be protected against external voltage. A shield with ground connection helps to keep external voltage away from the cables for the signals of the safety function STO.
Ground loops can cause problems in machines. A shield connected at one end only is sufficient for grounding and does not create a ground loop.
oUse shielded cables for the signals of the safety function STO.
oDo not use the cable for the signals of the safety function STO for other signals.
oConnect one end of the shield.
