Inst ToolsInst ToolsInst Tools
  • Courses
  • Automation
    • PLC
    • Control System
    • Safety System
    • Communication
    • Fire & Gas System
  • Instrumentation
    • Design
    • Pressure
    • Temperature
    • Flow
    • Level
    • Vibration
    • Analyzer
    • Control Valve
    • Switch
    • Calibration
    • Erection & Commissioning
  • Interview
    • Instrumentation
    • Electrical
    • Electronics
    • Practical
  • Q&A
    • Instrumentation
    • Control System
    • Electrical
    • Electronics
    • Analog Electronics
    • Digital Electronics
    • Power Electronics
    • Microprocessor
  • Request
Search
  • Books
  • Software
  • Projects
  • Process
  • Tools
  • Basics
  • Formula
  • Power Plant
  • Root Cause Analysis
  • Electrical Basics
  • Animation
  • Standards
  • 4-20 mA Course
  • Siemens PLC Course
Reading: Centrifugal Compressor Start Permissive and Interlocks
Share
Font ResizerAa
Inst ToolsInst Tools
Font ResizerAa
  • Courses
  • Design
  • PLC
  • Interview
  • Control System
Search
  • Courses
  • Automation
    • PLC
    • Control System
    • Safety System
    • Communication
    • Fire & Gas System
  • Instrumentation
    • Design
    • Pressure
    • Temperature
    • Flow
    • Level
    • Vibration
    • Analyzer
    • Control Valve
    • Switch
    • Calibration
    • Erection & Commissioning
  • Interview
    • Instrumentation
    • Electrical
    • Electronics
    • Practical
  • Q&A
    • Instrumentation
    • Control System
    • Electrical
    • Electronics
    • Analog Electronics
    • Digital Electronics
    • Power Electronics
    • Microprocessor
  • Request
Follow US
All rights reserved. Reproduction in whole or in part without written permission is prohibited.
Inst Tools > Blog > Control Systems > Centrifugal Compressor Start Permissive and Interlocks

Centrifugal Compressor Start Permissive and Interlocks

In this article, you will learn about the centrifugal compressor start permissive and interlocks used in the DCS and PLC automation systems.

Last updated: June 18, 2022 3:49 pm
Editorial Staff
Control Systems
No Comments
Share
4 Min Read
SHARE

Today in this article, you will learn about the centrifugal compressor start permissive and interlocks used in the DCS and PLC automation systems.

Contents
Centrifugal Compressor Start PermissiveCentrifugal Compressor Interlocks

Compressors are installed in every industry. Without compressors, an industry cannot run because Instrument Air, Nitrogen, and Plant Air are obtained from Air Compressors only. In other gas plants also, compressors play a very important role in increasing the pressure of gases.

A compressor has a lube oil system for proper control and lubrication of the gearbox and bearings. A seal gas system is used to provide isolation between the process gas to be compressed and the oil system. 

Centrifugal Compressor Start Permissive

Important Start Permissive in Centrifugal Compressor:

1) Most important permissive for starting the compressor is the seal gas pressure permissive. A minimum seal gas pressure is required for starting the lube oil system.

2)  Lube oil supply pressure to the gearbox should be greater than some defined pressure. For this auxiliary lube oil pumps (AOP) are running in auto mode to keep this pressure steady.

Two lube oil pumps are present in any lube oil system of a centrifugal compressor. If one pump cannot build sufficient pressure, then the other pump starts automatically.

When the compressor is running, the main oil pump (MOP) runs which is engaged with the gearbox. This pump maintains the lube oil pressure. When the compressor is running, the auxiliary oil pumps will be stopped automatically after some time delay.

3) Lube oil supply temperature to gearbox should be maintained in the defined range. Example temperature should be above 30 degrees centigrade and below 65 degrees Centigrade.

3) No trip signal from Machine Condition Monitoring System (MCMS). Generally, a contact is taken from the MCMS system for tripping the compressor on high vibration or high temperature of the motor winding. All should be healthy.

4) Inlet Guide Vane (IGV) should have a minimum opening (usually 3%-5% open) and Anti surge valve (ASV)/ Blow Off Valve (BOV) should be fully open

5) We can give a limited number of start commands to the main motor in a fixed time interval.

For example, Say we have given the start command to the main motor, and due to some problem the main motor got tripped immediately. Now you can give second start command after some time delay only. This time delay is maybe 5 minutes, 15 minutes, 30 minutes, 60 minutes, etc. The time delay will depend on your motor parameters or as per your control philosophy. This is for the protection of the motor.

6) Low suction pressure also won’t allow the Compressor to start in case of a booster Compressor like HP Air Compressor.

7) Inter-cooler and after-cooler levels should not be high

Centrifugal Compressor Start Permissive & Interlocks

Centrifugal Compressor Interlocks

Important Interlocks in Centrifugal Compressor 

1) Tripping on low seal gas pressure 

2) Tripping on high vibration

3) Tripping on low lube oil pressure 

4) Tripping on high lube oil temperature

5) Compressor unload on high motor current

6) On high discharge pressure, IGV starts closing. If still high, discharge pressure doesn’t come down, then ASV/BOV starts opening.

7) Tripping on low suction pressure

8) Tripping on individual stage inlet temperature high

9) Tripping on high condensate level in inter cooler and after cooler. A level switch is installed in the inter-coolers and after-coolers.

10) Tripping due to surging (surging is calculated typically using parameters like pressure, temperature, and flow. Sometimes motor current is also taken for calculating the surging)

Don't Miss Our Updates
Be the first to get exclusive content straight to your email.
We promise not to spam you. You can unsubscribe at any time.
Invalid email address
You've successfully subscribed !

Continue Reading

PLC Alarm and Trip Documentation
Workstation Healthiness Checks
What is a Feedback Control System? Types & Advantages
Steps to Import PlantPAx Add-On Instructions in Studio 5000
Inspection and Testing of Fiber Optic Cable
How Important is VPN for Control Engineers?
Share This Article
Facebook Whatsapp Whatsapp LinkedIn Copy Link
Share
Leave a Comment

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Stay Connected

128.3kFollowersLike
69.1kFollowersFollow
210kSubscribersSubscribe
38kFollowersFollow

Categories

Explore More

Steady-State Process Gain
Basics of Sinking and Sourcing – Automation System MCQ
Compare Modbus, Fieldbus, and Profibus
Definitions of Electrical Grounding
Why we use Diode Protection Modules ?
What is PID Controller Bumpless Transfer ?
How-to Create Instrument Loop Diagram (ILD)?
Vendor Document for Project Systems Architecture

Keep Learning

Instrumentation Commissioning

Commissioning Documents for Instrumentation Engineers

Open Platform Communication (OPC)

Open Platform Communication (OPC)

MODBUS ASCII Communication Protocol Explained

MODBUS ASCII Communication Protocol Explained

Transmitters 4-20mA Current Failure Alarm Limits

Transmitters 4-20mA Current Failure Alarm Limits

Schneider Electric Modicon M340 PAC

PLC vs PAC – Understanding the Key Differences and Similarities

Remote User Authentication

Security of Industrial Automation Systems

Fiber Optic Cable - Method of Joining and Fusion Splicing

Fiber Optic Cable – Method of Joining and Fusion Splicing

30 Concerns for Control System Philosophy (Industrial Automation)

30 Concerns for Process Control Systems Philosophy

Learn More

pn-junction-energy-diagrams

Energy Diagrams of PN Junction & Depletion Region

Flanged pipe fittings

What is Flanged Pipe Fittings ?

Calculate the Thermocouple Output millivolts

Calculate the Thermocouple Output millivolts

OPC-OLE-for-Process-Control

What is OPC ?

OB10 Time of Day Interrupt

Tia Portal – OB10 Time of Day Interrupt Organization Block

Downloading Free PLC software

Step by Step Guidelines for Downloading Free PLC software

Pressure Safety Valve Leak Test Procedure

Pressure Safety Valve Leak Test Procedure (PSV Testing)

Filters in Compressors

Filters in Compressors

Menu

  • About
  • Privacy Policy
  • Copyright

Quick Links

  • Learn PLC
  • Helping Hand
  • Part Time Job

YouTube Subscribe

Follow US
All rights reserved. Reproduction in whole or in part without written permission is prohibited.
Welcome Back!

Sign in to your account

Username or Email Address
Password

Lost your password?