Entec EVRC2A-N6-NT - Page 95

RECLOSER CONTROL EVRC2A-N6,NT http://www.entecene.co.kr
85
ENHANCED TECHNOLOGY
6.2.3. Setting Examples
Use of VD(CVD or RVD)
Case of VD(CVD or RVD) installed in Recloser, setup as follows;
Usable in Wye connection. Set VT2nd(v) 100 as Default.
PT Ratio is calculated as below.
Voltage
Ф-Ф
= Voltage
Ф-N
× SQRT(3)
Voltage
Ф-N
= VT 2nd(v) × VT Ratio
Hence,
15㎸
Ф-Ф
= 8.66㎸
Ф-N
, therefore 8.66㎸
Ф-N
= 55.5(V) × 155.9
If user line voltage between phases (Voltage
Ф-Ф
) is 11㎸, set VT2nd(v) of 40.7V and set VT Ratio
of 155.9 (11㎸
Ф-Ф
=> 6.35㎸
Ф-N
, 6.35㎸ = 40.7(V) × 155.9)
27㎸
Ф-Ф
= 15.59㎸
Ф-N
, therefore 15.59㎸
Ф-N
= 100(V) × 155.9
38㎸
Ф-Ф
= 21.94㎸
Ф-N
, therefore 21.94㎸
Ф-N
= 140.7(V) × 155.9
Use of External PT by User
Line is Wye connection type and has V
Ф-Ф
= 15㎸. If external rated PT is 14400 : 120, then VT
Ratio is 14400/120. Because of 15㎸
Ф-Ф
= 8.66㎸
Ф-N
, VT2nd(v) is 8.66㎸
Ф-N
/ 120 = 71.2V
Line with Delta connection type and has V
Ф-Ф
= 15㎸. If external rated PT is 14400 : 120, then
VT Ratio is 14400/120 and VT2nd(v) is 15㎸
Ф-Ф
/ 120 = 125V
Table 6-1. VT Ratios of External PTs
Line-Line
Voltage
Voltage Divider Potential Transformer
Wye connection Wye connection Delta connection
VT 2nd (v) VT Ratio VT 2nd (v) VT Ratio VT 2nd (v) VT Ratio
15㎸
100 86.6 71.2
120
(14400:120)
125
120
(14400:120)
27㎸
100 155.9 72.5
215
(25800:120)
125.6
215
(25800:120)
38㎸
100 219.4 73.1
300
(36000:120)
126.7
300
(36000:120)