KYZ pulse output help

[riccihull]

First of all, what exactly is a KYZ pulse output?

In my plant we have a "punch demand" meter that uses the KYZ from the utility meter to give an instantaneous load and also print it out on adding machine type paper.

I would like to replace this meter with something a little more modern, perhaps attach to the network. Is there a device that I can drop in to replace it?

We do have a power meter in parallel with the utility, I was also considering replacing it with a meter with trending capability.

Opinions?

 

[Skogsgurra]

The KYZ pulse output from meters is an old and very simple technique where one unit of energy corresponds to one pulse. Historically, it was generated by the rotating disk in the meter and there was one pulse/revolution.

The output used to be (and probably still is) a reed relay contact.

Any counting device that you can think of can be used to evaluate the KYZ pulse. Anything from a small PLC or micro to a PC or a dedicated data collector that can be bought from the meter producers.

Visit the Landis&Gyr or Enermet homepages for more information.

 

[RalphChristie]

If I am correct, a KYZ-meter is a three terminal switch (K, Y and Z) with K in the common position, Z in the Normally-open position, and Y in the Normally-close position. When a unit of power is measured, the meter changes the status of the switch.
See:

http://www.obvius.com/documentation/technotes/TN01-PulseOutputEnergyMeters.pdf

 

[Skogsgurra]

Thanks Ralph. I have only seen the form A contact. Or rather, the applications I have seen didn't use the form C contact to its full extent. I remember that a foundry (where it was very important to stay within limits - or the kWh above the limit would cost a fortune) had problems with interference from a VFD. With some filtering and use of the form C contact they could probably have solved that problem.

 

[dpc]

As I recall, if you only monitor one of the two contacts, you will need to double your kwH total. The KYZ was intended to go to a register that accepted both contacts and counted both contact closures.

 

[busbar]

The KYZ-pulse train has been around for many decades, and serves as a form of “parity check” in transferring watthour (or varhour, VA?hr, V²hr, A²hr, etc.) data. For KYZ applications, a degree of confidence is assured in that a KY-contact closure must be followed by a KY-contact opening, then KZ closure, KZ opening… If the equipment is so designed, it can be used for very high rates at very high {routinely million-dollar-a-month+ revenue} accuracy. Simple optocoupled form-A {MHz-scale} pulse trains are used in NIST-traceable energy standards by electric utilities in North America with 100-microwatthour/count rates having 600-volt, 150-ampere, 60-hertz inputs.

If you are using a KY- or KYZ-pulse train from the serving utility, they should be able to provide you with an exact K_e value in units of primary kilowatthours or megawatthours/count. Verify that the number you get is for the 2-wire or 3-wire form, or, as mentioned, your calculations will be off by a factor of two. The simplest of industrial timer/counter channels should work OK for your desired function.

If you install your own “revenue check” meter/transducer {and CTs+PTs} be extremely cautious in fingerpointing if readings don’t mesh.

 

[SSLA]

You mentioned that you want to connect the meter to a network. A number of products can do that. These will typically connect to a LAN via Ethernet and address them with a browser. Scan the web for meter high end manufacturers. The Ethernet port gets around the limited bandwidth of the KYZ pulse initiator and allows the meter to simultanously provide energy and power quality reading to a data system connected to your LAN.