Emerson VSG & VSSG Specifications download pdf (Page 104)

9 – 10

Section 9 • Step and PID Device Control Screens

Single Screw Compressor PLC Operation Manual • Vilter/Emerson • 35391CM

Liquid Injection Valve Screens

Figure 9-10. Liquid Injection Valve Screen

LIQUID INJECTION VALVE SETPOINTS

• Open Valve Above: Deﬁ nes the temperature at which

the liquid injection valve will open to minimum

position.

• Target Discharge Temperature: Deﬁ nes the desired

temperature of gas and oil discharging from the com-

pressor. The liquid injection valve position will adjust

to maintain this temperature.

• Deadband: Range above and below setpoint where

the controller will not make adjustments to the liquid

injection valve positon.

• Oil Separator Override Temperature: Separator Oil

Temperature must be above this temperature for the

liquid injection to operate.

• PID Tuning: PID Calculations displayed to aid in tun-

ing the PID loop.

• Loop Update Time: Deﬁ nes the PID controller loop

time. The PID calculation will update every cycle of

the loop update timer.

• Proportional Gain (Kp): Deﬁ nes the Proportional

Constant of the PID calculation.

• Integral Gain (Ki): Deﬁ nes the Integral Constant of

the PID calculation.

• Derivative Gain (Kd): Deﬁ nes the Derivative Constant

of the PID Calculation.

• Minimum Valve Open: Deﬁ nes the minimum liquid

injection valve position.

• Liquid Injection Valve Force: Allows the user to manu-

ally force the liquid injection valve to a settable po-

sition. Activating the Liquid Injection Valve Force

pushbutton will command the liquid injection valve

to go to the set position, and will override calcula-

tions from the PID Controller.

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Emerson VSG & VSSG Specifications Page 104