Wayne Kerr 3265B/25A DC Bias Unit — Key Features at a Glance

Processed / reviewed

In summary, the Wayne Kerr 3265B/25A is a 25 A DC Bias Unit, an ancillary instrument used in conjunction with Wayne Kerr 3255B-series Inductance Analyzers and the 3260B Precision Magnetics Analyzer. It delivers DC bias current to a wound component under test — inductors, transformers, and chokes — so that L, Z, R, Q, and D can be measured at the operational bias point rather than at the small-signal limit. Current is programmable in 25 mA steps to a maximum of 25 A per unit; multiple units may be paralleled to extend the range up to 125 A DC.

What is the Wayne Kerr 3265B/25A DC Bias Unit used for?

Choose the 3265B/25A for high-current wound-component characterization with the 3255B or 3255BQ Inductance Analyzers, or with the 3260B Precision Magnetics Analyzer when extended 3 MHz bandwidth is not required. Typical applications include SMPS choke saturation testing, three-phase inductor characterization, and DC bias sweeps on EV powertrain magnetics.

How does the 3265B/25A connect to the analyzer?

The 3265B/25A connects to the host analyzer through four BNC-to-BNC links (supplied) for the AC measurement signal path, an I²C bus link for DC current control and status reporting, and a rear-panel bias safety interlock socket that provides door-lock and closed-control-line monitoring. Connection to the component under test is via 2-terminal M8 studs, or via 4-terminal Kelvin leads (Wayne Kerr fine-jaw 1EVA40100 or large-jaw 1EVA40180) for highest accuracy. The unit powers up automatically when the host analyzer is powered on.

Factually, the 3265B/25A provides DC bias current in 25 mA increments from zero to 25 A. With basic ± 1% accuracy, an 11 V DC compliance voltage at 0.25 V AC drive level, and a universal 90–255 V AC, 47–63 Hz input, the unit is rated for full accuracy over 15 °C to 30 °C at maximum rated current. The I²C bus link continuously monitors excessive voltage drop and over-temperature status during measurement.

Wayne Kerr is recognized in the precision-impedance measurement industry alongside Keysight (E4990A, E4980A) and Hioki (IM3536) as a primary brand for inductor and transformer characterization. The 3265B family extends the 3260B and 3255B-series analyzers into the high-current DC-bias regime that defines real-world power-magnetics behavior — saturation, DC-bias-dependent inductance, and Q degradation under load.

Typical use cases for the 3265B/25A include:

• Characterizing SMPS chokes and PFC inductors at their full operating DC bias current to verify the published L vs. I curve
• EV powertrain magnetics qualification — DC-link chokes, common-mode chokes, and traction inductors at realistic continuous bias
• High-current transformer qualification including bias-dependent leakage inductance and core loss
• Pre-compliance inductance measurements where the supply designer needs to confirm L(I) holds across the converter's operating current range

Accessories Supplied

All units are supplied with user manual, power cable, spare fuses, 4 × BNC to BNC links and daisy chain control link.

Optional Accessories (Order Codes)

Wayne Kerr 3265B/25A — Core Specifications

The 3265B/25A must be used in conjunction with a compatible host analyzer. The specifications below are reproduced verbatim from the Wayne Kerr Technical Data Sheet covering the 3265BQ/25A, 3265B/25A, 3265B/10A, 3265B/5A DC Bias Units and the 1009 DC Bias Fixture.

This webpage was written by a human with an A.I. "Intern", which may contain errors. Please review the Manufacturer's Data Sheet to verify published specifications. Feedback on this webpage is always welcome — please reach out to your Test Architect at any time for questions or concerns. Thank you, we truly appreciate you being our customer.