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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
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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
Common out to R, Y, B
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 < 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
Connection for 4 CT meters
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
Common out to R, Y, B
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Current ReversalThis can occur because of:
Wrong connection HT TB < 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.
Connection for 4 CT meters
Link to Pictures ..
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Voltage
Load from
phantom load
Common out to R, Y, B
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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.
Connection for 4 CT meters
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
Common out to R, Y, B
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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.
Connection for 4 CT meters
Link to Pictures ..
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Voltage
from
phantom
load
Load from
phantom load
R
B
Y
N
R- IN
Y- IN
B- IN
Common out to R, Y, B
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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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