Transformer Oriented Steel Sheet: High Performance Sheet Solution

Grain oriented electrical steel (CRGO) is not a “general-purpose high-performance sheet.” It is a narrow, specialized material engineered for one job: carrying magnetic flux around a transformer core with minimum loss. If you specify it without knowing the grade table below, you either overpay for premium Hi-B or under-specify and run a transformer that overheats.

What CRGO Actually Is

CRGO is a low-carbon silicon steel (3.0–3.3% Si) cold-rolled with its grain boundaries aligned along the rolling direction. That alignment lets flux travel easily in the coil direction. However, it performs poorly at 90 degrees—consequently, CRGO cores always build from cut laminations or wound strip, never from randomly oriented sheet.

The Grade Table Buyers Actually Use

CRGO grades are defined by core loss at 1.7 T, 50 Hz (P₁.₇/₅₀):

Grade	Thickness	Core loss P₁.₇/₅₀	Typical use
27Q120	0.27 mm	≤1.20 W/kg	Distribution transformers
27Q110	0.27 mm	≤1.10 W/kg	Premium distribution
30Q120	0.30 mm	≤1.20 W/kg	General power transformers
30Q130	0.30 mm	≤1.30 W/kg	Cost-sensitive units
M4 / M5 / M6	0.27–0.30 mm	IEEE / IEC equivalent	Export to IEEE buyers
B18R080 / B23R085	0.18–0.23 mm	≤0.85 W/kg	Hi-B, high-efficiency

Hi-B (high permeability) grades add grain refinement; they cut no-load loss by 15–25% but cost 20–30% more. Specify Hi-B only when efficiency class (e.g., DOE 2016, Tier 2) demands it.

Coating: The Detail That Ruins Cores

CRGO arrives with a thin inorganic insulation coating. Two types matter:

• C-0 (bare): no coating, used when the core shop applies its own insulation.
• C-2 / C-4: organic-inorganic coating, punched and ready.

Specify the coating class on your PO. Otherwise, the mill ships its default.

Where CRGO Products Ship From Stock

We supply CRGO in several forms:

• Grain-Oriented Electrical Steel Sheet in standard slit widths for transformer core cutters.
• CRGO Transformer Steel Sheet in M4/M5 equivalent grades for export orders.
• Silicon Iron Sheet for Transformer in thicknesses from 0.23 to 0.35 mm.
• Cut Core Lamination for 11-0.4 kVA 100kVA Transformer as pre-cut, ready-to-stack EI or stepped-lap cores for small distribution units.

How to Specify in One Line

A complete CRGO order reads: “27Q120, 0.27 mm, slit to 140 mm, C-4 coating, P₁.₇/₅₀ ≤ 1.20 W/kg.” Leave out the coating or the slit width and you will wait for a custom re-slit.

Source CRGO for Your Transformer Line

Tell us your transformer rating, efficiency class, and required width. We will confirm available stock and quote coil or pre-cut laminations with a mill certificate.

• Email: vera.liang@ztwysteel.com
• Location: Xishan District, Wuxi, Jiangsu, China
• Supply range: CRGO and CRNGO silicon steel, pre-cut cores, electrical steel coil and sheet
• Grades: 27Q/30Q series, M4–M6, B-series Hi-B
• Documentation: MTC with core loss, induction, thickness, and coating class

We reply within one working day.