Raytech TR-MARK III 250V Three-Phase Transformer Turns Ratio Tester | Ratio 0.8–45,000, test voltage up to 250 V, automatic vector group detection

Raytech TR-MARK III 250V Three-Phase Transformer Turns Ratio Tester

Overview

The TR-MARK III 250V is a turns ratio tester for three-phase power transformers from Raytech of Switzerland. A three-phase two-winding transformer needs to be connected only once to fully automatically measure ratio, excitation current, phase deviation and error at all taps. It can control on-load tap changers or motorized de-energized tap changers, and automatically detects the vector group, the current tap position and the appropriate test voltage. It can also test PTs and CTs. The rack-mount TR-MARK III R 250V is available on request.

Key Specifications

• Ratio range: 0.8–45,000
• Ratio accuracy: 250 V: 0.8–5,000 ±0.06%, 5,001–10,000 ±0.1%, up to 40,000 ±0.4%; 100/40 V: 0.8–2,000 ±0.06%
• Test voltage and current: Selectable 1, 10, 40, 100, 250 VAC; max. 1 A; burden less than 0.05 VA
• Phase and current: Phase ±90°, ±0.05°; excitation current 0–1 A, ±0.001 A
• Display and operation: 5.7-inch color touch LCD; mouse and keyboard supported
• Interfaces and storage: 2 × USB 2.0, RS232; 10,000 internal records; built-in 1.9-inch thermal printer; T-Base Pro software
• Power: 90–132 / 180–264 VAC, 47–63 Hz; max. 150 VA
• Protection and durability: IP67 with lid closed; withstands a 1 m drop; operating temperature -10 to 55 ℃
• Dimensions and weight: 472 × 368 × 196 mm; 10.5 kg

Applications

• Acceptance testing of ratio, phase and tap changers on three-phase power transformers.
• PT and CT ratio measurement and preventive maintenance.

Specifications per the Raytech TR-MARK III 250V product page (raytech.ch, retrieved 2026-10-23).