Energy meters Tamper detials

8/10/2019 Energy meters Tamper detials

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Tamper Logics and Testing

Presented by

Ch.V.N.Rajesh


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Introduction

This Program explains about

1. Types of Tampers available in meter.

2.

Tamper features role in meters.3. How single phase and poly phase meters are

tampered.

4. Tampers testing methods.

5. What is the latest trend of tampers.

6. Storage mechanisms in our meters.


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Tampers in MeterPoly Phase meters:

Voltage Failure

Current Failure

Voltage Unbalance

Current Unbalance

Current Bypass

Current reversal Low Power factor

Neutral Disturbance

Magnetic logging

High ESD Detection

Power fail records

Terminal / Meter Cover open tamper

Single Phase Meters:

Reversal Tamper

Full Earth Load Tamper

Partial Earth Load Tamper

Magnetic Tamper

Current Bypass

Single wire Tamper

Terminal / Meter Cover open tamper


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Voltage Failure

1 2 3 4 5 6 7 8 9 10 11 12

Voltage

Load

N

B

Y

R=

0V

R- IN

Y- IN

B- IN

Common out to R, Y, B

Connection Error with HT terminal box

Taping missed while connectingMetering box

Internal cal links are not closed

Intentionally PT wire is removed forHT & LT CT meters

Relay connected to Internal PT wires

Impact is 33.33% less consumption inmeter

Threshold is


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Voltage Unbalance

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Volta

ge

Load

N

B

Y

R

R- IN

Y- IN

B- IN


This can occur because of:

Load unbalance

Intentionally add resistor to secondarywire for HT And LT CT meters

Resistor values modification byopening the meter

Impact :

Les consumption in meter

Testing :

Threshold is Vmax Vmin >30% ofVref

Tamper records when ever differencein voltages are greater than thethreshold value i.e for HT 4W 19.05 V,LT 72V, HT 3 W 33V

In Firmware Vref & 30% is the keyfactors, some of the times Vref for HT63V & LT 230V instead of 63.5 &240.

Connection for 4 CT meters

Link to Pictures ..


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Current FailureThis can occur because of:

Connection error in HT TB box

Full CT bypass in all meters

Primary CT failure in LT CT meters

CT failure in the meters

Testing :

Threshold is


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Current UnbalanceThis can occur because of:

Loose Connection in HT TB &LT CTbox

With out a proper planning of loaddistribution

Current bypass is detected through

Current unbalance for 3 Ct meters

Burden resistor change in metes

Testing :

Threshold isImax Imin >30% of

Ibasic

Tamper records difference in phasecurrent crosses the threshold value i.efor 1A 0.3A & 5A 1.5A

In Firmware Ibasic & 30% is the keyfactors, some of the times 1A CTtamping also threshold is 1.5A


Link to Pictures ..

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Voltage

from

phantom

load

Load from

phantom load

N

B

Y

R

R- IN

Y- IN

B- IN



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Current ReversalThis can occur because of:

Wrong connection HT TB &LT CT box

Wrong connection at meter end

Intentionally reverse the CT atprimary or secondary

Inside of the meter reverse thesecondary wire

Testing :

Threshold isve power >5% of

Vref* Ibasic & PF >0.2 or negative

power >1%

Tamper records phase negative power>5% and PF 0.2 or Negative totalpower is >1%

In Firmware 5% & 1% powerthresholds are the key factors.


Link to Pictures ..

1 2 3 4 5 6 7 8 9 10 11 12

Voltage

Load from

phantom load



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Current BypassThis can occur because of:

Burden modified to high values

By shorting Primary CT wires at meter

By shorting secondary CT wires at

meter box

Neutral CT reversal in the meter

Testing :

Threshold is Magnetitude of Ir+Iy+Ib-In >20% of Ib

Tamper records magnetitude of phasewise currents vectorial addition aresubtracted with neutral current isgreater than 20% of Ib

In Firmware 20% is the key factor.

Current unbalance and Current bypassshould not occur at same time.

With normal connection tampershould not false tri er.


Link to Pictures ..

1 2 3 4 5 6 7 8 9 10 11 12

Voltage

from

phantom

load

Load from

phantom load

N

B

Y

R

R- IN

Y- IN

B- IN



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Low Power FactorThis can occur because of:

Only capacitor bank is on

Testing :

Threshold is ve power


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Neutral DisturbanceThis can occur because of:

Phase and neutral inter change

Ac voltage applied to neutral

DC voltage is applied to neutral

Testing :

Threshold is Votage >150% of VrefTamper records phase voltage

>150% of Vref

In Firmware 150% of Vref is the

key factor, some of the times 125%

used to be as threshold.


Link to Pictures ..

1 2 3 4 5 6 7 8 9 10 11 12

Voltage

from

phantom

load

Load from

phantom load

R

B

Y

N

R- IN

Y- IN

B- IN



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Magnetic tamperThis can occur because of:

Magnetic field presence to the meter

Testing :

Magneto sensor card used to sense the magnetic filed, Card sends

signal to controller.Meter senses the magnetic field records as magnetic tamper and energy

recording is based on Vref*Imax*UPF.

In Firmware Imax recording is the key factor.

Link to Pictures ..


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1 Phase meter Tampers

Reversal Tamper isdeducted when ever there isphase difference of 180degrees between voltageand current.

Earth load is deductedwhen there is a difference inphase and neutral current.

Single wire condition isdeducted by using power CT,which produce voltage with

presence of VoltageBypass is deducted bycomparing phase and neutralcurrent.

Magnetic andterminal/meter cover opentampers same like poly

phase meters.

Link to Pictures ..


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New Tampers & Some Examples

High ESD applied to the meter, By using Spark plug.

It use to give high voltage around 35KV with spark duration of 600usec.

Terminal cover / Meter Cover open detection tamper recently included in meters.

In our meter we have three type of storage mechanism are availablea) Block Method

b) Sequential

c) Sequential Block

Link to Pictures ..


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Thank you


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