×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

VFD and starter P&ID symbols
2

VFD and starter P&ID symbols

VFD and starter P&ID symbols

(OP)
Anyone out there knows what symbols to use for a VFD and for a magnetic starter in a P&ID?
 

RE: VFD and starter P&ID symbols

For a DOL motor you don't need to show the starter just a circle with the motor number or drive Number e.g. P-101 for pump 101.
For a VFD a box beside the motor with the tag No inside e.g. VSD-101.
We don't usually show any electrical details i.e. Stop/Start buttons or interlocks unless they are something special otherwise it clutters up the drawing. You can show generic motor control on the cover sheet to show typical controls.
P&ID stands for Process & Instrument Diagram (not electrical)
The interlock logic is too complex to show on the P&ID this should be on a separate document
Roy

RE: VFD and starter P&ID symbols

You can choose how you want to display these things as long as you don't stray from any adopted specs or standards, and display them on a legend sheet so everyone can know what they are.

I agree with Roy that representing these can clutter a drawing, but my current client wants them on their P&IDs.

Their P&IDs will show a VFD or starter as a box, appropriately tagged, with several panel-mounted ISA devices (circles with lines through the middle, aka bubbles or balloons) for each function.

Starter coils themselves usually aren't shown, but if there is a Hand-Off-Auto (HOA) or On-Off switch associated with the starter, it will be shown as a hand switch (HS). Similarly, if there are indicating lamps to show when the motor is running, they will be shown as YL (event, state, or presence, Y, and light L). Some kind of feedback is usually provided to the control system in the form of a YS for an auxiliary contact on the starter or an IS if a current switch is provided.

Since VFDs usually have a start/stop or enable (or both) that can be indicated with one or more HS, as needed. If there is a fault relay, it can be represented by UA (multivariable alarm, since drives typically have more than one fault that will operate the single relay), or YA, since the drive is in a faulted state.

If an external speed reference is sent to the drive, this is indicated with a bubble designator that ends in Y, since it is converting (Y) the signal into speed. The first letter of the loop will be the identifying letter of whatever is being controlled by manipulating the speed (temperature, pressure, flow, etc.). If the measurement transmitter output is sent to the VFD directly so that the speed control is done by a control loop in the VFD itself, a device with a tag that ends in C can be included, e.g., if the fan speed is being used to control pressure from a pressure signal sent directly to the VFD, label the device PC.

My client has defined the standard VFD block for the type of VFD they use and the way they connect it. It always has the same bubbles, and is included on a legend sheet so that everyone always knows what it is. It has four bubbles: a HS for a HOA switch on the VFD cabinet, a HS for the remote Start/Stop signal, a YA for the fault alarm, and *Y for a external speed reference (substitute the process loop variable in for *). Standard starter blocks for MCC buckets have three bubbles: a HS for a HOA switch, a HS for the remote Start/Stop signal, and a IS (current switch) for proof-of-run feedback.

 

xnuke
"Live and act within the limit of your knowledge and keep expanding it to the limit of your life." Ayn Rand, Atlas Shrugged.
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.

RE: VFD and starter P&ID symbols

The firm I work for designs plants for large multi-nationals all over the globe.
I looked back at several projects showing the same pump with VFD for different clients. This VFD typically has a manual controller in the DCS.
As you can see by attached we taylor the P&IDs to suit the client. Sometimes we show lots of detail other times not.
As Xnuke says you can really do anything so long as you convey the information. We do a spreadsheet showing all the interlocks.
Regards
Roy

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources