Fuji Electric ALPHA7, User Manual

Page: 159 / 662

CHAPTER 2 WIRING
2-112
Safety Function
2

Employ double [EN1+] and [EN2+] inputs (with redundancy circuit) to ensure that the safety stop
function (STO) is not lost due to a single fault.
If a single fault is detected by the safety cutoff circuit, an alarm is output to external devices, and
the servo amplifier slowly stops the motor (free-run stop), even if the [EN1+] and [EN2+] status is
ON. (The alarm output function does not guarantee that an alarm will be output for all single faults,
however, compatibility with EN ISO13849-1 PL=e Cat. 3 is possible.)

The safety stop function (STO) is not designed to completely cut off the power supply and motor
electrically. Cut off the servo amplifier input power supply completely, and begin wiring and
maintenance work after 5 minutes or longer have elapsed.

A motor rotation equivalent to electrical angle of 180° may occur following a servo amplifier fault.
Employ designs that present no danger based on load conditions.
2.7.2.3 Safety Stop (STO) Test
Conduct a check once a day to ensure that the safety stop function (STO) is functioning normally.
2.7.3 Specifications
2.7.3.1 Function Block Diagram
Drive circuit
Motor
U
V
W
Power
supply
24 V power
supply
0V
Safety
switch
L1
L2
L3
EN1+
EN1-
EN2-
EN2+
Servo amplifier
Fig. 2.7.3-1 Function block diagram