This document discusses high voltage distribution systems (HVDS) as an alternative to low voltage distribution systems (LVDS) commonly used in India and Europe. HVDS brings distribution lines closer to loads using single phase transformers, reducing line losses. There are three types of HVDS - phase-neutral, phase-phase, and phase-ground. Phase-neutral HVDS is widely used in North America, with a neutral line extending from the substation to all nodes. Single and three-phase loads are served using single or multiple single-phase transformers connected in open delta or star-delta configurations.

1. HIGH VOLTAGE DISTRIBUTION SYSTEM

2. HIGH VOLTAGE DISTRIBUTION SYSTEM (HVDS)
Introduction
 The two widely prevalent distribution practices in
vogue across the world are:
 Low Voltage Distribution System (LVDS): This is
based on European practice, where three phase
transformer of considerable capacity is installed and
LV lines are extended to cater to a group of loads. This
system is best suited to meet the concentrated loads
of high load density
 This system now prevalent in INDIA is inherited from
the British.

3. HIGH VOLTAGE DISTRIBUTION SYSTEM
 High Voltage Distribution System (HVDS): This is
based on North American practice where three
phase or single phase HV line is taken as near the
load as possible and a distribution transformer of
appropriate capacity, generally one or more single
phase transformers, are installed to feed one or a
small group of loads, such that the length of the LV
lines is minimum or is eliminated altogether.
 This system is best suited for Rural areas of INDIA
to meet the scattered loads of low load density.

4. HIGH VOLTAGE DISTRIBUTION
SYSTEM
 For the distribution of same power, the comparison of
current, Losses, voltage drop with 100 as base is as
follows:
PARAMETER SФ 6.3 kV/440V
HVDS
CONVENTIONA
L 3Ф LVDS
CURRENT (A) 11 100
LOSSES (Kw) 8.5 100
VOLTAGE
DROP
12.7 100

5. HVDS USING SINGLE PHASE DTRS
There are three types of High Voltage
distribution system in vogue:
 Phase Neutral HVDS (PN-HVDS)
 Phase Phase HVDS (PP-HVDS)
 Phase-Ground HVDS (P-G HVDS)

6. HVDS USING SINGLE PHASE DTRS
Phase-Neutral (P-N)HVDS
 The system is widely adopted in North America.
 Under this system, the 11 kV main line from
substation is three-phase 4 wire (3 phases + Neutral)
and laterals are single-phase 2 wire line or two-phase
3-wire line or three-phase 4-wire line depending upon
the loads and feeding arrangement.
 The unique feature of the system lies in providing the
neutral right through the system, viz., from substation
to all nodes on the network.

7. HVDS USING SINGLE PHASE DTRS
 Single-phase Loads: 11 KV single phase line
(phase neutral) branch is extended from main
line and 1 No. 6350/230-0-230 V distribution
transformer is erected to feed single phase
loads.
 Three-phase loads: Three alternative
arrangements for feeding three phase loads
are described:

8. HVDS USING SINGLE PHASE DTRS
 (i)11 KV two-phase 3-wire branches are extended
from the main line and 2 Nos. of single-phase
6350/230-0-230 V distribution transformer is
connected, star on HV side and open delta on LV
side to feed three-phase loads, as shown in Fig.
3.1. In this arrangement, the effective capacity of
the transformer bank is 86.6% of total capacity i.e.
if two transformers of 10 KVA capacity are used,
the maximum three-phase load that can be fed is
17.32 KVA.

9. HVDS USING SINGLE PHASE DTRS
 (ii)11 KV three-phase, 4-wire line is extended
and 3 Nos. 6350/230-0-230 V single phase
transformers are connected, star- delta to feed
three-phase loads.
 (iii)Alternatively conventional three-phase
delta/Star distribution transformer also can
be used