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Modeling a Zig-Zag Grounding transformer
The following picture is the nameplate of a Grounding Zig-Zag transformer:
The information that we will use:
KVA rating: 160
Voltage: 7200
Ohms/phase: 13.2
Continuous Neutral amps: 42
The transformer’s X/R ratio is the other piece of information that’s not provided on the nameplate. This value will need to be assumed if it cannot be provided from the manufacturer.
Place a 2-winding transformer on the one-line drawing and double-click on it to bring up the Component Editor. Enter the nominal kva value (160), the connection configuration (primary is wye-grounded and the secondary is delta), and enter the primary and secondary voltages (7200 for both). If the voltages were defined for the line and load side, then those voltage will show (7200) as grayed out. Once these values are entered the full load amps value will be displayed (12.8). The Component Editor should now appear as shown:
Two adjustments need to be made. Set the transformer type to Zig-Zag and adjust the Full Load KVA value. The nameplate shows the continuous neutral amps are 42. Divide this value by 3, which equals 14. This is the ampacity rating of the transformer based on its Full Load KVA rating. If this value is set at 180KVA then the ampacity of the transformer will be 14.4 amps. (See screen shot below)
The information that we will use:
KVA rating: 160
Voltage: 7200
Ohms/phase: 13.2
Continuous Neutral amps: 42
The transformer’s X/R ratio is the other piece of information that’s not provided on the nameplate. This value will need to be assumed if it cannot be provided from the manufacturer.
Place a 2-winding transformer on the one-line drawing and double-click on it to bring up the Component Editor. Enter the nominal kva value (160), the connection configuration (primary is wye-grounded and the secondary is delta), and enter the primary and secondary voltages (7200 for both). If the voltages were defined for the line and load side, then those voltage will show (7200) as grayed out. Once these values are entered the full load amps value will be displayed (12.8). The Component Editor should now appear as shown:
Two adjustments need to be made. Set the transformer type to Zig-Zag and adjust the Full Load KVA value. The nameplate shows the continuous neutral amps are 42. Divide this value by 3, which equals 14. This is the ampacity rating of the transformer based on its Full Load KVA rating. If this value is set at 180KVA then the ampacity of the transformer will be 14.4 amps. (See screen shot below)