Rockwell Automation 20-750-ATEX PowerFlex 750-Series ATEX Option Module - Manual (Page 10)

10 Rockwell Automation Publication 750-UM003B-EN-P - July 2013
Chapter 1 Safety Concepts
ATEX Function The PowerFlex 750-Series ATEX option module can be configured to support
ATEX certified motors equipped with either a thermostat or a PTC-type
thermal sensor.
Thermostat Trip
When the circuit is configured to trip with a thermostat, the ATEX option
module supports a normally-closed, dry-contact thermostat. The safe off
function initiates when the ATEX option module detects that the contact is
open. This can be the result of a broken wire, or an over-temperature condition in
the motor.
Positive Temperature Coefficient (PTC) Trip
When the circuit is configured to trip with a PTC-type thermal sensor, the
ATEX option module supports sensors with characteristics according to
DIN 44081/DIN 440. The ‘Mark A’ measuring circuit on the ATEX option
module is designed in accordance to IEC 60947-8 or EN 60947-8. This circuit
trips when the motor temperature has reached its trip point, or an open-wire/
short-circuit condition is detected in the sensor circuit.
Loss of voltage to the measuring circuit also initiates the safe off function. This
voltage is sourced internally by the ATEX option module.
Figure 2 - ATEX Circuitry
ATTENTION: Risk of electric shock. If a motor insulation fault occurs, high
voltage can be present at the ATEX terminal block and wiring. Be sure that all
drive covers are installed when power is applied to the drive.
ATEX+
ATEX–
High Voltage
Possible
Isolation Safe Low Voltage
EnC
EnNO Thermal
Sensor Type
Switch Safety
Configuration
Switch
Latch
Relay Driver
Safe Shutdown
Signal
Reset Signal
Or
Field wiring to thermal sensor.
See
Connect the Thermal
Sensor Wires on page 22 .
Safety configuration switch to configure the
safety path for use with a safety option. See
Configure the Hardware on page 18 .
Terminals EnC and EnNO must be wired correctly
when a safety option is present in the drive. See the
important statements on
page 25 and page 26 .
ATEX trip signals pass through an
isolation barrier to protect the drive
in case of a motor insulation fault.
See
ATEX Monitoring on page 33 .
Thermal sensor-type switch selects
between PTC and thermostatic-
type thermal sensors. See
S1 Switch
Location on page 18 .
An ATEX trip latches the drive into a
safe state until a reset sequence takes
place. See
Restart the Drive after an
Over-temperature Fault on page 35 .
For installations that do not have the safe
torque-off or safe speed monitor safety options
present, the ATEX safety function uses the
safety signal on the backplane. See
Interface
Without a Safety Option on page 27 .