6
Series 70
Servo NXT - EtherNet/IP
Installation, Operation and Maintenance Manual
4.2 Power Connections
4.2.1 Input Power
Due to the power requirements of large electric
actuators, the Servo NXT EIP has a dedicated
power input separate from the EtherNet/IP
network cabling. This power input energizes not
only the Servo NXT EIP, but also the actuator
motor used to position the valve.
Power provided to the Servo NXT EIP should be
within 10% of the voltage listed for the actuator.
For example, a 24VAC actuator should have
power provided that has a voltage within 21.6
and 26.4VAC after voltage drops of the cabling.
Additionally, the power supply should be capable
of sourcing 5A per actuator, since the actuator is
capable of drawing large currents on startup.
Note:
24VAC actuators should have a dedicated
100VA transformer for each actuator
4.2.2 Heater (optional)
The S70 has the option of having a cartridge
heater installed at the factory. These 2 terminals
provide a connection point for this heater,
providing fused power to the heater from the
input power terminals.
4.2.3 Motor
The S70 actuator is driven by either a split
capacitor induction motor (120VAC or 230VAC
operation) or a brushed DC motor (24VAC or
24VDC operation). The Servo NXT EIP provides
power to the motor to operate the actuator
and position the valve based on the command
position provided by the scanner.
4.3 Factory Connections
One large terminal strip is provided on the
Servo NXT EIP for connections switches and
potentiometer internal to the actuator. These
connections are generally made at the factory
and should not require adjustment in the field.
4.3.1 Limit Switches
The switches attached to this terminal strip have
been set at the factory to be engaged when
the limits of travel have been reached, in other
words, when the fully open and fully close
positions have been reached. These switches
prevent the Servo NXT EIP from operating the
actuator to a point where the gearing could
bind up and become damaged. These switches
are engaged by a cam shaft coupled to the
output gear of the actuator, and the cams on
the cam shaft should be adjusted to ensure the
limit switches are engaged before any other
mechanical limits are reached.
The Servo NXT EIP provides a logic level voltage
at the Open (LO) and Close (LC) terminals of
this connection. Once one of the travel limit
switches is engaged, the switch at the applicable
connection will engage and pull this pin to 0V,
signaling the Servo NXT EIP to end operation.
For proper operation, both travel limit switches
should not be engaged at the same time. This
would prevent the Servo NXT EIP from operating
the actuator, and results in a limit switch fault.
4.3.2 Torque Switches (optional)
If the torque present on the output of the
actuator goes outside the rated torque listed
for the unit, then the actuator gearing could be
damaged. These switches detect the presence of
high torque on the output gear, and if activated,
put the Servo NXT EIP into a fault state. This
fault state prevents further operation until the
torque is reduced.
The Servo NXT provides a logic level voltage at
the Open (TO) and Close (TC) terminals of this
connection. If the actuator torque increases
above the rated torque, the switch at the
applicable connection will pull this pin to 0V,
signaling the Servo NXT to enter a torque switch
fault.
4.3.3 Handwheel Switch
The S70 actuator comes with an external
handwheel that can be pulled out to allow
for the valve to be positioned manually. If the
handwheel is pulled out or engaged, then a
switch is activated in the actuator, putting the
Servo NXT EIP into a fault state. This fault state is
active until the handwheel is pushed back in or
disengaged.
The Servo NXT EIP provides a logic level voltage
at the HW terminal of this connection. If the
handwheel is engaged (pulled out), this pin will
get pulled to 0V, signaling the Servo NXT EIP and
resulting in a handwheel fault.
