SURGE ARRESTER SELECTION ..
Project : 2.5MVA 34.5kV/400V Indoor Substation
Location : SM San Jose
Client : SM Prime Holdings Inc.
Date : Nov 2, 2015
I. PROJECT SCOPE OF WORKS
Supply and installation of 2.5MVA 34.5kV/400V Indoor Substation for SM San
Jose Del Monte.
II. OBJECTIVE
The objective of this study is to properly select the surge arrester at the HV
side of the power transformer without compromising the transformer’s HV BIL rating.
III. EQUIPMENT SPECIFICATIONS
Power Transformer
Brand : SHILIN
Country of Origin : Taiwan
Type : Oil-immersed Conservator Type
kVA Rating : 2500/3125kVA
Vector Group : Dyn11
Primary Voltage : 34.5kV
Secondary Voltage : 400/231V
Tap : 5 taps +/- 2.5%
BIL (HV) : 170kV
Ref. Standard : IEC-60076
*Please see technical specifications for reference
Surge Arrester
Brand : INAEL
Country of Origin : Spain
Type : Station Class, Gapless
Model : INZSP 30/10/2
Rated Voltage : 30kV
MCOV : 24.4kV
Residual Voltage under 8/20µS – 10kA (kV) : 73.2kV
Residual voltage under switching impulse – kV : 59.7kV
Location : 34.5kV MVSG
*Please see attached brochures for reference
#366 2nd ST.Bet. 9th & 10th Avenue brgy. 107, Caloocan City
TEL. No. 365-6793 & 365-3430
Website: www.chasia.com.ph
Email Add: info@chasia.com.ph
IV. SINGLE LINE DIAGRAM
Note: Surge arresters at First Private Pole are also to be installed.
#366 2nd ST.Bet. 9th & 10th Avenue brgy. 107, Caloocan City
TEL. No. 365-6793 & 365-3430
Website: www.chasia.com.ph
Email Add: info@chasia.com.ph
V. SELECTION OF SURGE ARRESTER MCOV IS BASED ON THE FOLLOWING
TABLE CONSIDERING MERALCO LINE IS GROUNDED NEUTRAL CIRCUIT
INAEL Surge Arrester’s available MCOV rating higher than 21.6MCOV is 24.4MCOV.
Thus selecting INZSP 30/10/2.
#366 2nd ST.Bet. 9th & 10th Avenue brgy. 107, Caloocan City
TEL. No. 365-6793 & 365-3430
Website: www.chasia.com.ph
Email Add: info@chasia.com.ph
VI. INSULATION COORDINATION
The generally recommended minimum protective margin, defined in IEEE Std. 141-
1993, 6.7.2 (Insulation Coordination), is 20% for impulse coordination (front-of-wave, full
wave) and 15% for switching coordination. The Shilin power transformer to be installed at
SM San Jose has a HV BIL rating of 170kV. The Inael surge arrester (INZSP 30/10/2) has a
residual voltage under 8/20µS – 10kA (kV) at 73.2kV and a residual voltage under switching
impulse at 59.7kV.
PRL2 = Basic Lightning Impulse Level / Lightning Protective Level = BIL / LPL
= 170kV / 73.2kV
= 2.3224
PML2 = Protective Margin
= (PR-1)100%
= (2.3224-1)100%
= 167.76%
PML2 has a margin of 67.76% which is greater than the recommended 20% margin. Thus,
the Inael Surge Arrester (INZP 30/10/2) will be sufficient to protect the Shilin Power
Transformer.
#366 2nd ST.Bet. 9th & 10th Avenue brgy. 107, Caloocan City
TEL. No. 365-6793 & 365-3430
Website: www.chasia.com.ph
Email Add: info@chasia.com.ph
VII. CONCLUSION:
VIII. REFERENCES:
a. OHIO Brass Arrester Application Table 4, 204-6 May 2012
b. Insulation Coordination, IEEE Std – 1993, 6.7.2 and 6.7.3.1
Prepared by: Noted by:
LEE RANDALL TIONGSON DANILO P. VILLADOS
Engineering Manager Operations Manager
Conforme by:
____________________________
Client Authorized Representative
#366 2nd ST.Bet. 9th & 10th Avenue brgy. 107, Caloocan City
TEL. No. 365-6793 & 365-3430
Website: www.chasia.com.ph
Email Add: info@chasia.com.ph
