Tenaga Nasional Berhad

Table Z: Planning Levels for Harmonic Voltages in TNB distribution systems 415V and below including
background harmonics
Odd Harmonics
Odd Harmonics
(Non-multiple of 3)
(Multiple of 3)
Even Harmonics
Order Harmonic Order Harmonic Order Harmonic
“h” Voltage (%) “h” Voltage (%) “h” Voltage (%)
5
4.0
7
4.0
2 1.6
11
3.0
3
4.0 4 1.0
13
2.5
9
1.2 6 0.5
17
1.6
15
0.3 8 0.4
19
1.2
21
0.2 10 0.4
23
1.2 >21 0.2 12 0.2
25
0.7
>12 0.2
>25 0.2+0.5(25/h)
The total voltage harmonic distortion level is 5%
Note: The above table shows the Engineering Recommendation G5/4 levels. TNB is in the process of adopting
IEC levels and the values in the above table will be updated later
2.3.7 Voltage Unbalance
2.3.7.1 All plant and equipment connected to the distribution system, and that part of the distribution system at each
connection site, should be capable of withstanding the following distortions of the voltage waveform in respect
of Voltage Unbalance at the planning stage.
) Under planned outage conditions, the maximum negative phase sequence component of the phase voltage
on the distribution system should remain below 1% unless abnormal conditions prevail.
) Under the planned outage conditions, infrequent short duration peaks with a maximum value of 2% are
permitted for Voltage Unbalance, subject to the prior agreement of TNB under the connection agreement.
TNB will only agree following a specific assessment of the impact of these levels on TNB and other
Customers’ plant and equipment with which it is satisfied.
38 TENAGA
NASIONAL B E R H A D