LEROY-SOMER
4946 - 2013.07 / a
POWERDRIVE MD2CS
27
en
InstallatIon and maIntenance
Chassis-mounted variable speed drive
connectIons
3.3 - STO-1/STO-2 inputs: Safe Torque
Off function
the sto-1 and sto-2 inputs are safety inputs that can be
used to disable the drive output so no torque at the motor
shaft is provided.
they are independent of one another. they are created by
simple hardware not connected to the microcontroller. they
acts on two different stages of the IGBt output bridge control.
to enable the drive, the sto-1 and sto-2 inputs must be
connected to the +24V source.
the opening of, at minimum, one of the inputs locks the
output bridge.
these 2 inputs can be used in conjunction to create a "safe
torque off" function with a logic combining 2 separate
channels.
In this configuration, the "Safe Torque Off" function is
guaranteed with a very high level of integrity in conformity
with standards:
- en 61800-5-2
- en/Iso 13849-1: 2006; Ple
- Iec/en 62061: 2005; sIl3
(cetIm approval no. cet0047520)
In a safety system, this built-in function enables the drive to
act as a substitute for a contactor so the motor can run in
freewheel mode.
the sto-1 and sto-2 inputs are compatible with self-tested
logic outputs in controllers such as Plcs, for which the test
pulse lasts for 1 ms maximum.
If the data sent by the 2 inputs is not identical, this generates
a drive trip. the Rl1 relay opens and the drive indicates
a "t.r./63" trip on the drive 2-digit display or "sto input
inconsistency" trip on the parameter-setting interface.
For correct use, the power and control connection diagrams
described in the following paragraphs must be adhered to.
• The STO-1/STO-2 inputs are safety components
which must be incorporated in the complete
system dedicated to machine safety. As for any
installation, the complete machine must be subject to a
risk analysis. The integrator must determine the safety
category which the installation must comply with.
• The STO-1 and STO-2 inputs, when open, lock the
drive, so the dynamic braking function is no longer
available. If a braking function is required before the
drive secure disable lock is applied, a time-delayed
safety relay must be installed to activate the locking
automatically after the end of braking.
If braking needs to be a machine safety function, it must
be provided by an electromechanical solution since the
dynamic braking by the drive function is not considered
as a secure disable function.
• The STO-1/STO-2 inputs do not provide the
electrical isolation function. Prior to any work carry out
on tre drive/installation, the power supply must therefore
be switched of an approved isolating device (isolator,
switch, etc).
3.3.1 - Single channel locking (SIL1 - PLb)
3-phase ac power supply, in accordance with safety standard
Iec/en 62061: 2005 and en/Iso 13849-1: 2006 - single
channel locking (sIl1 - Plb).
U
V
W
Px2
+24V Ref
DO1
STO-1
DI2
DI3
STO-2
DI4
DI5
+24V Ref
M
3
PE
PE
L1 L2
L3
POWERDRIVE MD2CS
safe torque off/drive
enable input
Run FWd/stop
Run ReV/stop
3.3.2 - Double channel locking (SIL3 - PLe).
3-phase ac power supply, in accordance with safety standard
Iec/en 62061: 2005 and en/Iso 13849-1: 2006 - double
channel locking (sIl3 - Ple)
U
V
W
Px2
+24V Ref
DO1
STO-1
DI2
DI3
STO-2
DI4
DI5
+24V Ref
M
3
PE
PE
L1 L2
L3
POWERDRIVE MD2CS
output stage of a
safety relay
Run FWd/stop
Run ReV/stop