Two-Channel Monitoring - BONFIGLIOLI ACTIVE CUBE Series Applications Manual

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Complement to operating instructions (32 pages)

Table Of Contents

Table of Contents

Triggering of function "Safe Torque Off"

Safe Torque Off can be achieved by:

−

Intentional triggering during operation in order to stop a drive and safely prevent

restarting, e.g. for maintenance work on a machine.

−

Triggering by actuation of an emergency stop switch or monitoring of protective

systems, e.g. safety door.

−

Detection of an error. The drive may only start again after the error has been

acknowledged and eliminated.

Detection of an error through self-diagnosis

Application example:

The danger zone near a transport conveyor is monitored by a light grid. If anybody

enters the danger zone, the light grid is interrupted. The DC 24 V supply for the digi-

tal inputs STO of the function „Safe Torque Off" is switched off and the frequency

inverter output stage is disabled. The drive coasts to a standstill. Disconnection from

mains supply is not necessary. Communication via field bus or addressing via the

terminals is still possible. An external brake which stops the motor can be addressed.

4.1

The STO function (Safe torque off) is realized via two channels in the frequency in-

verter (redundant design). Via two redundant monitored stop paths with no-voltage

release (STOA and STOB), the frequency inverter is switched off safely even if an

error occurs and the control voltage fails at the same time. Thus, the drive is stopped

safely if an error occurs. An error is identified and can then be repaired (e.g. by re-

placing of a unit). Triggering can be effected, for example, via a two-channel contac-

tor control with two release circuits and redundant disconnection of the main current

or via a sensor or emergency stop switch with two contacts and separate cable

routing to the evaluation unit.

The stop paths are monitored cyclically every 32 ms. Both stop paths are designed

identically.

Via the digital inputs S1IND (STOA) and S7IND (STOB), two DC 24 V control voltages

of a protection device are applied. If the protection device is actuated, the control

voltages are interrupted and the pulse block is activated; energy supply to the motor

is switched off. Disconnection is effected at a delay of less than 10 ms.

If the function STO is triggered, the overriding controller has no more influence on

the pulse block

and a release commanded by the operator or the superior PLC.

One single error will not result in a failure of the safety function.

If the pulse block is set, the controller release is reset. If the pulse block is set, no motor revolving

field is generated.

Actuation of safety relay