Different Reading's Between kWH Meters on 11kV Switchgear

Are the two feeders in parallel?

Line impedance can create the diference.

The 2 feeders are in series Sir.

Just because the CTs have ratios of 150/5 and 200/5 doesn't mean the load is split between the two feeders in proportion to the CT primary values. Unless the meters do not match the CT ratios to which they are connected, it looks to me like the second feeder has only 1/40 the load of the first (if they are continuous loads). Better take a look at what is on each of the feeders, and add up their kVA.

Besides, if you are looking at kWH, you have the time element involved. One of the loads may only operate intermittently, but at higher load. Again, add up the kVA loads on each feeder, and also correlate that with how often and how long they run.

What is your concern? What are you trying to prove or disprove or hypothesise?

Are you concerned that they are different?

I doubt very much that you know what you have in the way of metering.

1. You likely have 2 meters on the same feeder, rather than one meter on each of two feeders.

2. One meter (150/5) is likely set up with the multiplier of 30 and reads correctly.

3. The other meter (200/5) is not setup with the multiplier thus reading 1/40 of the power.

4. The readings of the 200/5 meter being in the 40-80 kW range are very small compared to the capacity of the 11 kV line and 200A CTs which is in the order of ~3800kVA You need be multiply these readings by 40 to obtain true power/energy.

You need to provide a circuit showing how these units are connected! The only way you should expect two power meters to agree is if the energy goes first through one meter and then through the other on its way to a single load or set of loads.

If, as you seem to indicate, they are on two different circuits, then there is no way they should agree. Any constant ratio between the loads will be distorted by different inductances, capacitances, and resistances of the leads and loads, as well as (in most cases) different times of operation etc.

The scenario is like this;

the first meter (meter 1) is connected to a switchgear (switchgear No.1) with a rating of 150/5A @ 11kV

the second meter (meter 2) is connected to a switchgear (switchgear No.2) with a rating of 200/5A @ 11kV

power travels from switchgear No.1 @ 11kV to switchgear No. 2 @ 11kV to a 2000kVA stepdown transformer and then to a 2500A Main Switch Board (MSB) with an output voltage of 240V (phase - neutral) and 415V (phase to phase) which then goes to various loads.

The question is why doesn't the 2 meters (meter 1 and meter 2) show the same reading when they are on the same circuit. Is it possible that they are not calibrated properly since meter 2 shows a reading of 1/40 of meter 1. By the way the meters that i'm using are Socomec Diris A40 digital power meters.

Yes there are some losses on the copper cable from switchgear No.1 to switchgear No. 2 as they are about 100m apart but the kWH readings between the 2 meters should not be so far off.

I already told you WHY!

The meter on the 200/5 CT is not applying the x40 multiplier.

Have you checked that yet giantleo?

Check the meters for proper setup such as the following:

Scaling correct?

Range correct?

Multiplier correct and in use/active?

CT Ratio correct?

Meter display resolution set the same? (If the resolution is not set the same in both meters the number of decimal places will vary. The second appears to be 'clamped' at two (2) while the first appears to be set at four (4) which will cause even further disagreement and confusion due to "rounding up or down" of display output.

It appears that the 150/5 energy meter gives a direct reading with CT ratio considered while the 200/5 energy meter does not consider the CT ratio and hence the reading must be multiplied by 40 as already pointed out by a friend.

The meter should read kWh direct by applying the multiplier before display.

The reading multiplier must be settable for use with different CTs.

Meter needs a closer scrute. (it is 2012 and post processing a meter reading is just not on)