Download SCHEDULE-III (Volume-A) TECHNICAL

Spec--HT TVM (DLMS)
- 21 -
Annexure- B
Tamper Logics for HT-TVM
Persistence time: 5 Min.
Restoration Time : 1 Min. (60 Sec.)
Tamper Events
1. Missing Potential
a. Voltage
b. Current
2. CT Polarity Reversal
a. Line Current in tampered phase
b. Power Factor.
3. CT Open
a. Line current in tampered phase
b. Line current in other phases
c. Load current in tampered phase
4. CT Bypass
a. By Pass Current
5. Current unbalance
a. Maximum current – Minimum current
6. Neutral Disturbance
a. DC current injected on neutral from
load side by mean of electronic circuit
using diodes after removal/ disconnection
of neutral.
7. Interference of Magnetic field
a. Presence of Magnetic field
Occurrence
Restoration
< 20% Vb
> 10% Ib
> 40% Vb
Ignored.
> 5% Ib (in reverse > 10% Ib (in
direction)
forward direction)
>0.1
>0.1
< 2% Ib
> 10% Ib
> 10% Ib
> 5% Ib.
>5% Ib.
Ignore
> 20% Ib
< 10% Ib (current
in tampered phase)
> 30% Ib
< 10% Ib
If
meter
detect removal
voltage greater than injection
1.25 times of Vref.
of
Magnetic field which removal
affects
accurate magnetic field.
Meter recording.
DC
of