Manufactured Flex RangeMag-Flex Pre-Magnetization System
A locally engineered power-transformer pre-magnetization system that dramatically reduces inrush current during energization — mitigating voltage sags, nuisance overcurrent tripping and electromagnetic shock.
Mag-Flex connects to a transformer’s low-voltage terminals through a small interface transformer and, on command, ramps voltage and current up in a controlled linear manner until it matches the transformer’s no-load current — magnetizing it safely before the breaker closes. Built around an ABB DCT880 thyristor controller (or DCS880 DC-drive with saturable reactor) and an AC500 PLC, with full interlocking. Engineered and assembled by PPE Technologies.
Built around safe transformer energizationEnergize transformers without the inrush penalty
Mag-Flex provides a controlled approach to energising transformers, helping manage the electrical impact that can occur during start-up. By preparing the transformer before full energisation, the system supports smoother integration into the network and more predictable operation from the moment power is applied.
Cuts transformer inrush current
A controlled linear ramp matches the transformer’s no-load current, so energization no longer draws the high inrush that causes voltage sags, nuisance protection tripping and electromagnetic shock.
Standalone and self-powered
Runs from a 400 VAC auxiliary supply — substation or generator — and connects to the transformer’s LV terminals through an interface transformer that provides galvanic isolation, voltage matching and vector-group correction.
Safe, fully interlocked operation
Hard and soft interlocks tie into the 220 kV and 33 kV breakers and their protection, with potential-free contacts, a ready-to-close handshake, a timed operating window and a cool-off lockout.
Typical project environmentsWhere Mag-Flex can be positioned
Mag-Flex is suited to electrical networks where transformer energisation needs to be carefully managed to maintain system stability. Its controlled pre-magnetisation approach makes it particularly valuable across installations where network strength, continuity and predictable start-up behaviour are important.
Power stations
Controlled energization of generator step-up and station transformers without inrush disturbance.
Transmission & distribution
Pre-magnetization of large 220/33 kV and similar power transformers before breaker close.
Mining & heavy industry
Protects networks with limited fault capacity from inrush-driven voltage sags and tripping.
Weak & islanded networks
Generator-fed and black-start environments where inrush would otherwise trip protection or disturb sensitive loads.
Technical overviewEngineering the energisation process
Mag-Flex is designed around the critical stage before a transformer is brought fully online, helping create a more controlled transition into normal operation. The technical overview alongside provides the key engineering context behind how the system manages this process and integrates with the wider electrical network.
Product category
Power-transformer pre-magnetization system for inrush-current mitigation
Ratings
400 VAC input / 0–400 VAC output, 50 Hz; max output current 450 A, controlled output 0–371 A; 24 VDC control; IP55; operating temperature −10 to 60 °C
Ramp control
ABB DCT880 thyristor power controller, or DCS880 DC-drive with saturable reactor (arid-area option); controlled linear ramp-up matched to the transformer no-load current, ramp time adjustable 30–120 s
Interface & isolation
Output interface transformer providing galvanic isolation, voltage matching and vector-group correction; input/output MCCBs (-Q01/-Q02), output surge protection and fused isolator; connects to transformer LV terminals or NECR
Control & interlocks
AC500 PLC with potential-free interlock inputs and outputs; ties into 220 kV / 33 kV breakers, protection and synch-check; ready-to-close handshake, 180 s full-current window, approx. 30-minute cool-off lockout
Dimensions & weight
Approx. 1000 × 600 × 1800 mm (L×W×H); approx. 500 kg packed
Manufacturing
Engineered, assembled and factory tested by PPE Technologies
Product resourcesExplore the Mag-Flex resources
The supporting material expands on the Mag-Flex approach to controlled transformer energisation, providing added context around the system, its engineering principles and its place within wider network planning. The resources below offer a useful next step for understanding the solution in greater depth.
Read More
Transformer winding terminology
A transformer winding is a set of conductors arranged to form one electrical circuit around the transformer’s magnetic core. The primary winding is the winding associated with the incoming electrical circuit, while the secondary winding is associated with the other electrical circuit. These terms describe the two sides of transformer construction without specifying a particular connection arrangement.
Transformer magnetic-core terminology
The magnetic core is the part of a transformer’s construction that provides a path for magnetic flux between the windings. Core limbs are the portions around which windings may be placed, and yokes join the limbs to complete the core structure. These terms refer to physical transformer components and do not indicate a system rating, operating condition, or site application.
Mag-Flex Flyer
A concise introduction to Mag-Flex, outlining its purpose and role in controlled transformer energisation.
Mag-Flex Technical Specification
A focused technical reference covering the system’s engineering basis, operating approach and key specification details.
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Discuss your transformer energization requirement
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