SWEEP FREQUENCY RESPONSE ALALYZER

Introduction:

The Doble M5500 Sweep Frequency Response Analyzer (SFRA) is the latest generation of SFRA diagnostic instrumentation from Doble. With exceptionally fast sweep speeds, an expanded frequency range, and a dynamic range exceeding 150 dB, the M5500 provides an effective solution for evaluating the mechanical integrity of transformers, reactors, and other winding-based equipment. Combined with the intuitive operation and powerful diagnostic capabilities of the new SFRA v6 Software, the M5500 makes SFRA testing and analysis easier, faster, and more productive.

By measuring the frequency response of a transformer, the M5500 can help identify physical movement and other abnormalities affecting the windings, core, and internal connections. The instrument applies an excitation signal to the transformer and measures the resulting response. Comparing these measurements with established baseline data or results from similar units enables users to identify deviations that may indicate internal mechanical problems.

The M5500 helps reduce uncertainty regarding apparatus condition by providing objective and repeatable evidence of mechanical integrity or winding movement. It can be used to assess transformer deterioration, determine whether a transformer is suitable for return to service following a fault, and identify potential damage resulting from transportation.

Doble recommends establishing an SFRA baseline as part of the factory testing of new transformers and performing repeat testing following major transportation events, including changes in transportation mode or crane lifting operations. SFRA testing can also be performed following system faults and as part of a routine transformer maintenance and diagnostic program.

Frequency Range:

The M5500 provides frequency-response measurements from 10 Hz to 25 MHz. For transformer applications, Doble recommends a default measurement range of 20 Hz to 2 MHz, as there is generally limited diagnostic value in measurements outside this range.

The recommended 20 Hz to 2 MHz diagnostic range covers the most important areas of transformer assessment: Core and magnetic properties, Winding movement and deformation, Interconnections, leads, and tap changers

Resolution and Measurement Capability:

The M5500 measures frequency response at intervals defined by the user. Its default Tuned Frequency list provides a frequency distribution consistent with other Doble SFRA instruments and supports testing in accordance with IEC 60076-18.

The instrument can be configured for either logarithmic or linear frequency scaling, while maintaining a constant excitation level for each frequency measurement.

The M5500 also provides automatic scaling for individual frequency measurements and can optionally apply adaptive filtering. These capabilities contribute to an overall dynamic range of more than 150 dB within the default 20 Hz to 2 MHz frequency range.

Benefits:

• Helps verify transformer performance and mechanical integrity
• Supports reduced maintenance costs and extended transformer service life
• Identifies issues such as core movement, winding deformation and displacement
• Detects potential faulty core grounds, partial winding collapse, and hoop buckling
• Helps identify broken or loose clamping structures
• Supports detection of shorted turns and open windings
• Suitable for routine maintenance and investigations following suspected faults or abnormal events
• Provides highly repeatable measurements, enabling subtle changes in frequency response to be identified for diagnostic purposes

Key Features:

• Lightweight, rugged, and portable test instrument
• Typical sweep speeds of 15–30 seconds, reducing overall testing time
• Default frequency range of 20 Hz–2 MHz
• Expanded frequency range of 10 Hz–25 MHz
• >150 dB dynamic range within the default frequency range
• Wired or wireless connection to the controlling PC
• Includes SFRA v6 Software for instrument control, testing, and analysis
• User-selectable logarithmic or linear frequency scaling
• Automatic scaling of individual frequency measurements
• Optional adaptive filtering
• Tuned Frequency list supporting frequency distribution consistent with Doble SFRA instruments and IEC 60076-18
• CE marked for electromagnetic compatibility, safety, and hazardous-substance requirements

The Doble M5500 SFRA combines high-speed measurement, exceptional dynamic range, and powerful analysis capabilities to provide reliable insight into the mechanical and electrical condition of transformers and other winding-based apparatus. Its highly repeatable measurements make it a valuable tool for factory baseline testing, post-transportation assessment, post-fault investigation, and routine condition monitoring.

Technical Parameters:

Excitation Source

Channels: 01

Frequency Range: 10 Hz – 25 MHz user defi ned, within instrument frequency range

Output Voltage (pk-pk into 50 Ohms): User selectable between 10 V (default) and 2.5 V

Output Protection: Short circuit protected

 Source Impedance: 50 Ohms

Measurement Channel

Channels: 02 

Sampling: Simultaneous 

Frequency Range: 10 Hz – 25 MHz 

Max. Sampling Rate: 100 MS/s 

Input Impedance: 50 Ohms 

Recommended Calibration Interval: 01 year

Data Collection

Test Method: Sweep Frequency

PC Communication: USB/Wireless

Frequency Range: 20 Hz - 2 MHz (default), user defi ned within instrument frequency range 

Number of Points: 1045 points (default) 5000 points max per decade (log) 32,000 points max (linear) 

Dynamic Range: (20 Hz - 2 MHz) >150 dB 

IF Bandwidth: <10% of measurement frequency, adaptive

Point Spacing: Variable, Linear or Logarithmic

Data Display/Export/Analysis

Tabulation: Frequency/Magnitude/Phase 

Export Formats: CSV/IEC/CIGRE, SFRA v5 

Plotting: Frequency vs. Magnitude/Phase/ Impedance/Ratio 

Analysis: Difference, Cross-Correlation, Leakage Channel, Ratio

Standard of Compliance

Electromagnetic Compatibility (EMC): EN 61326-1:2013 EN 55011 Class A Group 1 EN 61000-4-2,3,4,5,6,8,11 Environmental: 1 IEC 60068-2-1,2,6,27,30,31 

Safety: IEC 61010-1 EN 61010-1 UL 61010-1 CAN/CSA C22.2 No. 61010-1-12 

RoHS: Directive 2011/65/EU with amendment 2015/863/EU

Available Models: M5500, M5400, M4100, M7100

Product Link: https://www.doble.com/product/m5500/