Accelnet & Stepnet Plus Panels STO Manual
16-01338 Rev 00
Page 20 of 34
Copley Controls
The STO function operates completely independently of the control core of the drive and is
implemented entirely in hardware. It does not depend on the control core for its operation and the
control core of the drive has no control over the STO function.
7.6.7 +HV and AuxHV DC Power Supply
The power supply used to provide the +HV and AuxHV drive power must have protections to limit the output
voltage to 100Vdc or less even in a single fault condition. Furthermore the power supply output must have
galvanic isolation from AC mains that meets the requirements for reinforced or double insulation..
7.6.8 STO DC Power Supply
DC power for STO circuits should be +24 Vdc and must be supplied by power supplies with an SELV rating.
This ensures that the maximum voltage output will be limited to +60 Vdc.
7.6.9 Wiring to the STO Inputs
Electrical connections to the STO inputs must meet the requirements for fault exclusions for short circuits
between conductors and short circuits between conductors and other conductive parts or earth or the
protective bonding conductor. Fault exclusion requirements are given in ISO 13849-2 and IEC 61800-5-2.
Toward this end, the STO cable connector is a crimp and poke type in order to meet the relevant fault
exclusions. The contacts and connector provide spacing that is greater than the minimum creepage and
clearance of 1.24 mm. that is required for fault exclusion when considering the FMEDA (Failure Modes,
Effects, and Diagnostic Analysis) of the system..
7.6.10 Periodic Test Requirements
In order to meet the diagnostic coverage requirements for Cat. 3, PL d, the STO function must be checked at
least once per year. See section 9 for specific details.
