The Wayne Kerr 3220A is a 20A DC bias unit designed to extend the measurement capabilities of the Wayne Kerr 3245 Precision Inductance Analyzer. It enables accurate characterization of inductors, coils, and transformers under DC bias conditions by injecting a controllable DC current through the device under test. Multiple units can be paralleled to achieve bias currents up to 100A, making it essential for applications requiring inductance analysis across varying DC operating points.
Technical Specifications
DC Bias Current
• Single unit: 0.2A to 20A in 0.1A steps
• Paralleled units (up to 5): 1A to 100A maximum
• Programmable control
Measurement Parameters (with 3245 Analyzer)
• Inductance (L), Capacitance (C), Resistance (R)
• Dissipation Factor (D), Quality Factor (Q)
• Impedance (Z), Phase Angle
• DC Resistance (Rdc)—unavailable when DC bias is active
• Turns Ratio (transformer measurements)
Frequency Range
• 20 Hz to 300 kHz (with 3245 Analyzer)
AC Stimulus Levels (from 3245 Analyzer)
• Voltage: 10 mV to 5V programmable; normal range 250 mV to 1V RMS
• Current: 1 mA to 100 mA programmable; normal range 25 mA to 100 mA RMS
Accuracy
• Basic accuracy: 1.0%
• Calibrated at 25°C with temperature multipliers provided
• Corrections required above 10 kHz due to capacitive loading; no corrections needed below 10 kHz
Power Requirements
• 400 W per unit
• Auxiliary fuses: 0.25A-T (230V) or 0.5A-T (115V)
– Key Features
• Requires BCI-A interface cards and 3245A software (identified by “A” suffix on rear panel)
• Single unit stacks on top of 3245; two or more units require rack mounting
• Programmable bias current in 0.1A increments
• Maintains full frequency response of 3245 Analyzer
– Typical Applications
• Inductance measurements under DC operating bias
• Characterization of power inductors, chokes, and transformers
• Evaluation of magnetic component behavior across load conditions
• Transformer turns ratio verification
– Compatibility & Integration
The 3220A is a dedicated accessory for Wayne Kerr 3245 Analyzers equipped with BCI-A interface support. Up to five units can be paralleled for maximum bias current expansion to 100A. Proper configuration and rack mounting are essential for multi-unit installations.
