1
Rotork Fairchild PAX1 Motor Set Pressure
Regulator
User’s Manual
Product Overview
The PAX1 Motor Set Pressure Regulator is a flexible
low voltage DC powered linear actuator coupled to
one of five Fairchild precision pressure regulators
capable of controlling pressure ranges of 0-0.5 psig to
0-3000 psig and housed in a flameproof enclosure.
The unit is inherently lock in last place as the actuator
will maintains its position upon loss of electrical
power.
The PAX1 can be actuated open loop using two
optically isolated switch closure inputs (Up and Down)
to change the pressure regulators setpoint. The PAX1
will continue to change the pressure regulator
setpoint in response to the input until either of the
adjustable range limits are reached.
The PAX1 has an isolated 4-20 mA control input to
proportionally control the pressure regulator setpoint.
There is a 1-5 vdc non isolated control input as well.
In analog control mode, the unit is fail freeze upon
loss of either control signals.
The actuator features UP and DOWN push buttons
under the cover to facilitate commissioning and to
permit local control of the
pressure regulator’s
setpoint
. There is an 8mm (5/16”) female hex motor
drive interface under the cover to allow manual setpoint control in the case of loss of electrical power.
The actuator includes two fully adjustable 1A, 250VAC SPDT alarm relays (one High and one Low)
providing alarm function when the pressure regulator output pressure reaches critical values. The relays
are magnetically latched so the alarm switch states are maintained when the power is disconnected.
This allows accurate alarm function on systems that remove power from the actuator between
adjustments to conserve power as is typically done in solar powered installations.
The PAX1 offers an optional optically isolated electronic 4-20mA feedback output. This feedback feature
is functional for both the pulse control and analog control configurations. The unit must be powered to
facilitate the feedback output function.
