Transformer Display
The Transformer Display is a class of
To show this display select Network > Transformers Controls in the Model Explorer.
The Transformer Display contains the following fields by default:
From Bus Number and Name
From Bus number and name. The From Bus is the tapped side. You may view either the Quick Power Flow List or the bus view display for the From Bus from the local menu.
To Bus Number and Name
To Bus number and name. You may view either the Quick Power Flow List or the bus view display for the To Bus from the local menu.
Circuit
Two-character identifier used to distinguish between multiple transformers joining the same two buses.
Status
The service status of the transformer. This field is toggleable.
Type
Type of transformer. Possible values include
Fixed The tap positions are fixed
LTC The tap ratio changes to regulate bus voltage
Mvar The tap ratio changes to regulate reactive power flow
Phase The phase angle changes to regulate real power flow
Tap/Phase
Indicates the tap ratio for LTC and fixed transformers and the phase shift angle in degrees for phase-shifting transformers.
If the value of this field is Yes, the transformer will automatically change its tap or phase angle to keep the regulated value within the specified regulation range, provided that the Auto XF field of its associated area is set to Yes and transformer tap/phase control has not been disabled for the entire case. The Auto XF field of individual areas is set from the Area Display, and case-wide transformer control can be set from the Power Flow Solution tab of the Simulator Options Dialog. Click on this field to toggle its values.
Reg Bus
For an LTC transformer, this is the number of the bus whose voltage is controlled by the transformer. For phase shifting transformers, the real power is always controlled at the tapped bus.
Reg Value
For an LTC transformer, this is the present per unit voltage at the regulation bus. For a phase shifting transformer, this is the present real power flow through the transformer measured on the "from" (tapped) side.
Reg Error
The error is the difference between the regulated value and the respective limit of the regulation range specified by Reg Min and Reg Max. If the regulated value is within the regulation range, then the error is zero. The error is negative if the regulated value falls below the regulation range, and it is positive if the regulated value exceeds the regulation range.
Reg Min, Reg Max
Minimum and maximum values for the regulation range. For LTC transformers, these fields represent per unit voltage at the regulated bus. For phase shifting transformers, these fields represent actual MW flow through the transformer measured on the "from" (tapped) side. Because transformers use discrete control, the maximum regulation value must be somewhat greater than the minimum value.
Tap Min, Tap Max
For LTC transformers, these fields specify the minimum and maximum tap ranges for the transformer. For phase shifting transformers, these fields specify the minimum and maximum phase shift angle in degrees.
Step Size
The per unit step size for tap changing transformers. This step size is usually determined by dividing the total range of transformer operation by the number of tap positions available.