Table of Contents
Advertisement
Chapter 4 WiringEB3000
4-9 Drive's STO Function
This section introduces the STO function and how to use it in elevators. For more information, please
contact Delta. Read the following precautions to ensure safety.
An improper use of STO (Safe Torque Off) functions would cause serious
injuries or death. Make sure the entire system or machinery uses the STO
function that complies with safety requirements. When implementing STO
functions into a safety system of machines, a thorough risk assessment and
validation must be carried out to ensure compliance with safety standards such
as ISO/EN 13849, IEC/EN 61508, IEC/EN 62061.
When using a PM (Permanent Magnet) motor, even if drive output is disabled by
STO function, a breakdown of two output transistors can cause current to flow
through the motor winding, resulting in a rotor movement for a maximum of 180
electrical angle. Make sure that such circumstance does not affect the safety of
applications when using STO functions. Failure to comply can result in death or
serious injuries.
The STO function disables the drive output, but neither cuts off the drive power
supply, nor electrically isolates the drive output from input. When performing
maintenance or installation at drive's input and output side, always turn off the
drive's power supply. Failure to comply can result in death or series injuries.
If the motor is subjected to an external force, use a mechanical break that meets
the safety requirements of the entire system or machinery to stop the machine
connected to the load. When an external gravitational force is applied to vertical
axis while the STO function is active, the motor may still move. Failure to comply
may cause serious personal injury or death.
Connect the safety input into the equipment in compliance with the safety
requirements. Failure to comply can result in death or serious injuries.
Make sure to remove the wirings between STO1, STO2 and E24V terminals that
were installed prior to shipment. Otherwise, STO circuit will not be able to work
normally, and may cause personal injury or even death.
It takes a maximum of 3 ms for the drive to output since input terminals STO1
and STO2 are OFF. The sequence setting to trigger terminals STO1 and STO2
should confirm both terminals remain ON for at least 3 ms in order to properly
interrupt the drive output. But this may cause STO input deactivated.
DO NOT use STO (output terminals SMO+ and SMO-) for any other purposes. It
can be used only for monitoring STO status or detecting malfunctions in STO
inputs. The monitor output is not considered as a safety output.
4-24
Advertisement
Table of Contents
