Safety Circuit - Toshiba V Series User Manual

Chapter 4 Installation and Wiring

4.11 Safety circuit

4
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Relay contacts open when power supply stops or power line is broken in the normal relay
sequence. This is one of the fundamental characteristics of the relay. Based on this
concept, S2 is made failsafe in such a way that all outputs are turned off in the event of
emergency stop, power failure, and error shutdown.
However, it is not the best way to incorporate all functions in the S2 program considering
such a case that the CPU or I/O module fails, or the I/O cable is broken.
Configure the safety circuits shown below outside S2 with full consideration to the failure
of S2 and broken cable.
(1) Emergency stop circuit
(2) Safety interlocking circuit (forward and reverse, etc.)
Configure emergency stop and safety interlocking circuits outside S2. Otherwise, serious
accidents may occur due to failure or malfunction of S2. There is also the risk of damaging the
equipment.
transformer
S2
emergency
starter
stop
MC
interlocking
(forward and reverse etc.)
Warning
S004F
Xm
0.5s TON Tm
Tm
MCS
R1
MC
Input module
R2
Xm
output module
Ym
output module
MC2
MC1
model 2000 Sequence Controller S2 User's Manual -Basic Hardware-
Ym
Ym is ON during RUN
Wating for power up of the
DC power supply
DC
power
supply
(+) (-)
R2 Relay
Xm is turned to ON aftor
the DC power supply is
set up.
R1 Rl is ON during RUN
MC MC
The power for loads is
OFF when emergency
stop is active.
MC1
MC2