What Are Transformer Knowledge?

1. What Are Transformer Capacity Specifications?

The capacity of a transformer is its ability to transfer electrical power, measured in units of KVA (kilo-volt-ampere) or VA (volt-ampere) for smaller scales. Here are the main classifications of transformers based on various factors:

Based on Insulation and Cooling Media: Transformers are mainly divided into:

Dry-Type Transformers: Use air for insulation and cooling. They come in two main types:
SCB: Epoxy resin-cast dry-type transformer.
SGB10: Non-encapsulated H-class insulated dry-type transformer.
Oil-Immersed Transformers: Use oil as an insulation and cooling medium.
Based on Voltage: Voltage levels vary based on needs, such as 1000KV, 750KV, 500KV, down to lower levels like 20KV or 6KV.

Based on Energy Efficiency Level: Energy-efficient models are coded as SJ, S7, S9, S11, S13, S15.

Based on Power Capacity: Capacity is specified based on the amount of power the transformer can transfer, such as 50KVA, 100KVA, 200KVA, up to 5000KVA.

Based on the Number of Phases: Transformers can have either:

Single Phase
Three Phases
Based on Core Structure and Material: Core types vary, for example:

Silicon steel-laminated core transformers
Wound core silicon steel transformers
Amorphous alloy core transformers (lighter and more efficient).

2. What is the Unit of Transformer Capacity?

The capacity of a transformer is measured in KVA (kilo-volt-ampere) or VA (volt-ampere), not in KW (kilowatt). In AC (alternating current) systems, VA and KVA are used because they represent apparent power, which is the product of the effective voltage and current.

Why is KVA used instead of KW? In AC circuits, there is also reactive power created by capacitive and inductive loads. This reactive power does not consume energy but affects the transformer’s load design, so VA or KVA is a more accurate measure of capacity.