Editing Safe torque off

[[File:sto.jpg|thumb|Motor velocity decaying to zero after STO has been activated.]]
Safe torque off a.k.a. STO is a motor drive function that disables drive's ability to produce torque with motor and also prevents unintentional motor start-up. STO is built with [https://en.wikipedia.org/wiki/Redundancy_(engineering) redundancy] a way that guarantees the torque removal torque even in the case of single failure of any component of the system.
==Usefulness==
Built-in STO in drive provides following
;Pros
*Eliminate the need of power cutting relay or contactor 
*Can provide dynamic braking of motor under STO condition instead of letting motor free-wheel which usually increases safety
*Reduce cost of safety circuity
*Simplify wiring
;Cons
*Most STO implementations not safe with brush DC motors and also may cause AC motor to lock-up in certain magnetic pole angle (thus motor can still produce torque but cannot rotate more than 1/2 revolutions)
==STO in Argon servo drive==
[[Argon (servo drive)]] has 4-way STO function making it one of the most fail safe implementations available. Safety is being provided by four simultaneous actions:
*Removing AC input power from power stage by the means of internal safety rated relay
*Cutting gate drive voltage from power stage rendering power stage inactive
*Activating dynamic braking of motor
*Software (firmware) disabling motor control
The cutting of AC power makes Argon safe even with DC motor and does not allow AC motor lock up.
==STO in IONI servo/stepper drive==
[[IONI Servo & Stepper Drive]] has one dedicated digital input for STO. When STO2 line is logic low, drive's power stage control is de-energized making it unable to drive any current or voltage to motor coils. In addition to this, drive firmware reads STO2 status and disables motor control signals.
@@ Line 1: / Line 1: @@
 [[File:sto.jpg|thumb|Motor velocity decaying to zero after STO has been activated.]]
-Safe torque off a.k.a. STO is a motor drive function that disables drive's ability to produce torque with motor and also prevents unintentional motor start-up. STO is built with [https://en.wikipedia.org/wiki/Redundancy_(engineering) redundancy] a way that guarantees the removal of torque even in the case of single failure of any component of the system.
+Safe torque off a.k.a. STO is a motor drive function that disables drive's ability to produce torque with motor and also prevents unintentional motor start-up. STO is built with [https://en.wikipedia.org/wiki/Redundancy_(engineering) redundancy] a way that guarantees the torque removal torque even in the case of single failure of any component of the system.
 ==Usefulness==
 Built-in STO in drive provides following
@@ Line 19: / Line 19: @@
 ==STO in IONI servo/stepper drive==
 [[IONI Servo & Stepper Drive]] has one dedicated digital input for STO. When STO2 line is logic low, drive's power stage control is de-energized making it unable to drive any current or voltage to motor coils. In addition to this, drive firmware reads STO2 status and disables motor control signals.
-[[Category:Technology]]
-[[Category:Glossary]]
-[[Category:Argon features]]
-[[category:IONI features]]