Term/abbreviation
Explanation
SBA
Feedback, SBC active
t
SBA,Out
Max. delay for diagnostic feedback (≤ permissible reaction time when a
safety function is requested
1)
+ 10 ms)
n
Rotational speed
1) see Technical data, SBC safety data
Tab. 6 Legend for SBC timing
Requirements for the brakes
•
Check the brakes used for suitability for the application.
As a rule, the brakes used are holding brakes. That means, the brakes are well suited to keep the
motor at a standstill.
The internal holding brake of the motor is also used for the safety function SBC. Observe the following
boundary condition:
–
The holding brake must be designed for the load torque to be stopped.
–
The specifications for the holding brakes permit a certain movement until the complete holding
torque is reached. This must be taken into account in the design of the vertical axles and configur-
ation of the safety function SBC.
–
“Reserves” should be planned for in selecting the motor, e.g. operation at a maximum 2/3 of the
nominal torque. The holding brakes in the motors are usually designed so that, at loads below
70 % of the nominal torque, the motor shaft comes to a standstill without coasting.
–
Depending on the hazard situation, the holding brake must be designed with a correspondingly
increased nominal torque.
–
In designing the holding brake, the additional load torque for the brake test must be considered.
The number of clamping and braking applications is limited for the clamping unit due to wear.
1. Observe the corresponding specifications in the data sheet.
2. Replace clamping unit before the maximum number of clamping applications is reached.
3. Replace clamping unit when the emergency brake features of the clamping unit are used. Pay
attention to the number of permissible emergency braking applications.
Brake test
•
Check whether a brake test is required. The DGUV information sheet “Gravity-loaded axis”
provides information on this.
4.1.4
Safety function SS1
Fig. 8 Symbol SS1
The function described here implements the safety function SS1 according to EN 61800-5-2.
The safety function SS1 is used when, in the application, the motor must be braked and then the
energy supply to the motor safely switched off, and there are no further requirements for a targeted
standstill of the drive (controlled stop, stop category 1 according to EN 60204-1).
Product overview
15
Festo — CMMT-AS-...-S1 — 2018-02