Views: 0 Author: Site Editor Publish Time: 2026-07-06 Origin: Site
Rated Capacity: 1000 kVA. This indicates the continuous apparent power output the transformer is designed to handle safely under standard cooling conditions.
Voltage Combination: High Voltage (HV) of 22 kV and Low Voltage (LV) of 0.4 kV, making this a step-down distribution unit.
Tapping Range: ±5% or ±2 × 2.5%, allowing manual configuration of winding turns via the tap changer to manage voltage variations on the grid.
Connection Group Symbol (Vector Group): Dyn11 (or Yyn0 / Yzn11 depending on system requirements), defining the winding configuration and phase displacement.
Guaranteed Losses: A No-load Loss of 1150 W and a Load Loss of 11330 W, reflecting the highly optimized magnetic core and copper windings designed by premier power transformer manufacturers.
Impedance Voltage: 6.0%, which dictates the fault current capacity and voltage regulation profile of the system.
No-load Current: 0.7%, indicating the minimal excitation current required to energize the magnetic core when no load is connected.
Every electrical parameter listed on this certified placard is deeply interconnected. Below, we break down the critical engineering definitions, design implications, and diagnostic functions of each fundamental nameplate category to ensure your maintenance teams can interpret these parameters with absolute precision. Understanding these metrics is vital when evaluating equipment from top-tier power transformer manufacturers to ensure optimal grid integration and long-term operating efficiency.
The rated capacity defines the maximum continuous apparent power the transformer can deliver without exceeding its design temperature limits. For the 1000 kVA TSTY unit analyzed above, this capacity serves as the thermal and electrical limit of the system. Operating a transformer beyond this rating for extended periods accelerates the thermal aging of the winding insulation and paper, significantly reducing the service life of the equipment.
The rated voltage on the nameplate specifies the line-to-line operating voltages for both the primary (high-voltage) and secondary (low-voltage) windings. In our example, the transformer steps down 22 kV (22,000 V) distribution-level power to 0.4 kV (400 V), which is the standard three-phase utilization voltage for industrial machinery and commercial facilities. The voltage ratio (22:0.4) directly determines the turns ratio of the primary to secondary copper coils.
Utility grid voltages fluctuate based on load demands and distance from the substation. To compensate for these variations and maintain a stable output voltage (such as 400V), nameplates feature a tapping range (e.g., 22 kV ± 5% or ±2 × 2.5%). By adjusting the off-circuit tap changer to different positions, technicians can alter the active turns in the primary winding, thereby fine-tuning the output voltage to match localized grid conditions.
The vector group notation (such as Dyn11, Yyn0, or Yzn11) represents the physical winding connection scheme and the phase angle displacement between the high-voltage and low-voltage sides.
For example, in a Dyn11 connection:
D: High-voltage winding is Delta-connected.
y: Low-voltage winding is Star (Wye) connected.
n: The neutral point of the Star connection is brought out to an external terminal for grounding.
11: The low-voltage phase lags/leads the high-voltage phase by 30 degrees (represented as 11 o'clock on a clock diagram).
Matching the vector group is crucial for safety and system compatibility, particularly when running transformers in parallel.
Transformer efficiency and operating costs are directly influenced by two core thermal losses:
No-load Loss (Iron Loss): The energy consumed to magnetize the silicon steel core, which remains constant as long as the transformer is energized, regardless of the load. For our 1000 kVA reference model, this is optimized at an ultra-low 1150 W.
Load Loss (Copper Loss): The $I^2R$ resistive heating losses that occur in the windings when current flows through them, which increases quadratically with the load. For our reference model, this is 11330 W under full-rated load.
Minimizing these losses directly translates into significant annual operational cost savings.
Expressed as a percentage (6.0% in our 1000 kVA model), the impedance voltage represents the primary voltage required to circulate rated current through the secondary winding when the secondary terminals are short-circuited. This parameter is vital for electrical safety engineering because it dictates the maximum short-circuit current the transformer will allow during a fault, which in turn determines the sizing and rating of downstream circuit breakers and protective devices.
The no-load current is the small fraction of rated current (0.7% in our reference model) required to establish magnetic flux in the core when the secondary side is completely open-circuited. A low no-load current percentage indicates a high-quality, highly permeable silicon steel core construction, demonstrating superior manufacturing precision and lower excitation energy requirements.
