SLIDE 1 www.calmet.com.pl Poland, 65-472 Zielona Gora, Kukulcza Street 18 1
Problems:
1. Accuracy of Energy Meter ( SOLVED )
- 2. Connection correctness in
measurement circuit
- 3. CT ratio and phase shift error
- 4. Burden of Current and Voltage
Transformers
L1 L2 L3
S1 S2 P1 P2 S1 S2 P1 P2 S1 S2 P1 P2
1 2 3 4 5 6 7 8 9 11
A B a b A B a b A B a b
Potentaial Transformers Current Transformers Energy Meter under Test
On Site Current Transformer Testing
SLIDE 2 www.calmet.com.pl Poland, 65-472 Zielona Gora, Kukulcza Street 18 2
RS232
Power 10VA 1A 85-265V
I3
CALPORT 100 Plus calmet
*I3 *I2 *I1 U3 U2 U1 U0 I2 I1 U1 U2 U3 L1 L2 L3
S1 S2 P1 P2 S1 S2 P1 P2 S1 S2 P1 P2
1 2 3 4 5 6 7 8 9 11 N
Umax 40kVAC Umax 600VAC
Calport100 Plus Analyser & Tester of Energy Meters and Network
SLIDE 3
www.calmet.com.pl Poland, 65-472 Zielona Gora, Kukulcza Street 18 3
Results of Connection Correctness Test
Correct connection Primary Current Ip2 connected in reversed way Interchanged Secondary Windings IS2 & IS3
SLIDE 4
www.calmet.com.pl Poland, 65-472 Zielona Gora, Kukulcza Street 18 4
CT Ratio & Phase Shift Error
Ip – measured value of primary current Is – measured value of secondary current Ip/Is – measured CT Ratio Ipn/Isn – nominal value of CT Ratio ε ε ε ε – CT Ratio Error dϕ ϕ ϕ ϕ – CT Phase Shift Error Example: CT ratio and phase shift error test CT: 25A/5A in phase L2
SLIDE 5 www.calmet.com.pl Poland, 65-472 Zielona Gora, Kukulcza Street 18 5
CT Burden Test
ε ε ε ε – CT Ratio Error in [%] [%] Percent of Nominal Power of CT - Sn
100% 25%
Limits of Accuracy Typical Working Area
1 2 3 4 5 6 7 8 9 11
Example:
Ip Is
Current Transformer CT Connecting Wires
Us1 Us2
2 2
0,0175 2 10 0,35 1
CU P
mm m l m R S mm ρ Ω ⋅ ⋅ ⋅ = = = Ω
2 2 2
5 0,35 8,75
P P
P I R A VA = ⋅ = ⋅ Ω =
Energy Meter under Test Rp – wires Resistance Pp – Power losses in Wires
SLIDE 6 www.calmet.com.pl Poland, 65-472 Zielona Gora, Kukulcza Street 18 6
RS232
Power 10VA 1A 85-265V
I3
CALPORT 100 Plus calmet
*I3 *I2 *I1 U3 U2 U1 U0 I2 I1 U1 U2 U3 L1 L2 L3
S1 S2 P1 P2 S1 S2 P1 P2 S1 S2 P1 P2
1 2 3 4 5 6 7 8 9 11 N
CT Burden Test by means of Calport100Plus
Connection diagram during CT Burden Test
SLIDE 7
www.calmet.com.pl Poland, 65-472 Zielona Gora, Kukulcza Street 18 7
CT Burden Testing - examples
Correct, full power usage (99.88% of Sn) Nominal Power Sn is exceeded (125.2% of Sn) Current Transformer with nominal power Sn=20VA
SLIDE 8
www.calmet.com.pl Poland, 65-472 Zielona Gora, Kukulcza Street 18 8
Conclusions Extended measurement functions and graphic representation of results enables full test of Energy Measuring System on Site. Tested is not only Energy Meter but also all additional accessories like CT and PT. Tested are also working conditions of equipment by checking the wiring and burden (load) of transformers.
