Power Monitoring Device

[redengineer]

Hi,

I am looking for a device that needs to monitor power flow on two 138kV transmission lines. The simple device specs are:

1. Calculate power from analog inputs (voltage and currents) and trigger based on a user defined threshold power with time delays.

2. Device should have logic function capabilities and be able to do summation of analog inputs.

I have researched and found that the devices that are capable of the specs but the draw back is that most of the devices offer only one set of voltage inputs and some decices do not have the capability to expand voltage inputs. I need atleast two. Moreover, some do not offer logic functions and summation functions.

The fault recorders offer these functions but I am looking into more of a protection class device like relays. I know that a device such as this can be built using transducers and timers a digital device is expected.

If anyone has applied or come across any devices, please let me know. I wanted second opinion from some of the experts out here. As I am new to this forum, pardon my mistakes. Thanks.

RedEngineer

 

[Skogsgurra]

I would use a couple of standard power transducers and add the outputs, analogue way. Google "power transducer" to find a lot of suitable devices. If you use 0-5 V outputs, you can just series connect them to get the summation you want. A simple threshold relay and a timer would do the rest. Or, use one of the new "programmable relays" to do the threshold and logig needed. I have used the Siemens LOGO! for similar purposes. But there are other, similar devices that do the same thing.

And, of course, you can sum mA outputs by just connecting them in parallel. If you have a 0/4-20 mA output, then use a 250 ohms resistor to get the ten volts from 2x20 mA.

Gunnar Englund

http://www.gke.org

--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[ScottyUK]

The modular protection relays like ABB's RE216 certainly have the capability for this kind of task but they seem a little overkill for this type of application unless you have money to throw at the job. A few calls to the bigger substation automation vendors will probably set you on the right track: any of the relays capable of switchgear bay level control should be capable of doing what you need. What can your existing relaying do?

skogsgurra's ideas are good too - are you expected to develop a solution youself or find a ready-made device capable of doing everything? Even in the latter case you will probably need to develop some form of program.


----------------------------------

Sometimes I only open my mouth to swap feet...

 

[redengineer]

Thanks for the information guys. After having a word with the project manager, they prefer to buy a ready made device from the shelf. They prefer not to build it from transducers. I agree with you ScottyUK that the devices out there are overkill for simple application like this.

As this is the first time that we are implementing this, there are no exsisting relays that we have.I will look into relays capable of switchgear bay level control. I appreciate your help and ideas. Have a good day.

RedEngineer