Frequency Converter

Frequency converters allow instrumentation to communicate as a single, integrated system by changing the output frequency of one device into a readable input for another device. Sometimes called a frequency changer, f/l-f/f frequency converters are used for rotating machinery where speed is monitored and converts rotation to mechanical speed. They can also match new speed sensors to original units and control process temperature, pressure, or flow without the use of a separate controller.

Universal f-l/f-f Frequency Converter

• Measures frequencies up to 100 kHz
• 2.3 kVAC, 3-port galvanic isolation
• Custom U/I trigger levels
• Advanced input limits for increased safety
• Fast response time, <30ms
• Universal power supply
• Low power dissipation
• Bluetooth, data logging, modbus
• NAMUR sensor error detection
• Low cut-off function (L.COF) enabled
• All terminals over-voltage protected (24 VDC), polarity protected and short-circuit protected

4225 Frequency Converter

4225 Frequency Converter by PR Electronics

The 4225 is a universal f/l-f/f frequency converter that is capable of receiving NAMUR, NPN, Contact NPN, PNP, Tacho, TTL, S0, and special voltage or current AC frequencies and converts them into programmable unipolar or bipolar mA / V frequency or relay. Equipment such as fans and pumps can be optimized based on information transmitted directly from the engine via the 4225 frequency converter. This also removes the need for secondary controllers while increasing accuracy and improving response time, which often reduces energy consumption in addition to reducing wear on equipment from excess use resulting in an overall reduction of operation costs.

Sophisticated Frequency Changer

Signal Conditioning Frequency Changer
• Accuracy: <0.06% / span
• Temperature coefficient: 0.006%/°C
• Response time: <30 ms
• Low power consumption 2.5 W
• Can be mounted side by side, horizontally, and vertically, without air gap, on a standard DIN rail up to 140˚F
• Excellent signal/noise ratio (> 60 dB), 18-bit output converter
• NAMUR NE21 and NE43, UK CA, UL-508 approvals

How A Frequency Converter Works

Converting Frequencies

Frequency converters allow various instrumentation to communicate together by converting an AC frequency to a DC frequency. Through the use of a frequency converter, AC outputs from equipment like an engine can directly be used to signal operating conditions for other instrumentation, such as a fan that requires a DC frequency input. Since many types of instrumentation require a DC input, frequency converters are commonly used in industrial processes, manufacturing, and power utilities to allow equipment to work as an integrated system.
AC Frequency Converter to DC

4225 Product Line

Multiple Configurations for Any Need

Complements the 4000 series multifunctional product range with a highly flexible and universal frequency converter. Based on the strong foundation of the PR 4000 series products with the well-known and unique features such as front display programming, simulation, universal power supply and the PR 4500 series communication interfaces.
Common input with programmable trigger levels and sensor supply 4225A:
• 4225A: 1 analog output and 1 relay
• 4225B: 2 relays
• 4225C: 1 analog output and 1 frequency output
AC Frequency Changer to DC

Input / Output and Specifications

Universal Power Supply for Frequency Converter 4225
• Universal Power Supply: 21.6…253 VAC / 19.2…300 VDC
• Input: NAMUR, NPN, PNP, Tacho, TTL, & S0
• Dual output with rogrammable bipolar mA / V frequency or relay
• Six output relay settings including windows, setpoint, and latch functionality
• Active/Passive Current Output: ±23 mA / 0…23 mA
• Buffered Voltage Output: ±10 VDC
• Digital Output: NPN & PNP; 0…100 kHz with programmable logic level 5…24 V

Secure and Easy Programming

• Real time Modbus or Bluetooth communication via PR 4500 series detachable interface for configuration, monitoring, and diagnostics
• All programming can be password protected
• 2-point process calibration
• Programmable trigger levels -0.05…6.5 V
• Programmable sensor supply 5…17 V
• Simulation of process value during commissioning and maintenance
• Linearization: Linear or square root function

Communication Interfaces

4501, 4511 and 4512 Display Programming

CProgram directly via the push-buttons and the unique PR electronics menu structure.

4511 and 4512 Digital Interface

• 4511 introduces Modbus RTU communication to your PR 4000/9000 device, an easy and cost-effective digital interface
• With 4512 you can program your PR 4000/9000 devices or activate datalogging via Bluetooth, using an iOS/Android device running the free PR electronics PPS app
Live Monitoring

• Live process values
• Minimum 69 available engineering units
• Device output level or tag number
• Device and signal status icons

Programming Standard Setup

• Configuration of input / output types
• Engineering units
• Scaling
• Relay set up if applicable

Programming Advanced Setup

• Password
• 2 point calibration
• Simulation
• Load/ save configuration
• Relay latching if applicable


• Flashing display indicating error
• Error code
• Error help text for easier diagnosis
• Maintains loop integrity

Real Time Process Data

Digital communication for your measurement points via 4511


Bluetooth communication for measurement points via 4512

• Modbus RTU slave – RS485 interface
• 2.5 kVAC galvanic isolation on the Modbus port
• Read / write configuration, calibration, process values, simulation
• PR Preset Software (PPS) app (free download for iOS and Android)
• Easy programming
• Live process and error monitoring
• Data and event logging (30 days / 1 sec) with read-out
• Data retention and real-time clock backup
• Data analysis in your preferred program via .csv file data export

(Video) Navigating Through Display of 4500 Communication Interfaces

Get attached to better asset management with detachable operator interfaces. Access your devices through detachable local operator interfaces, remote operator interfaces, and gateways. Our approach to asset management offers inexpensive future-proofing of your installed base to new communication protocols.

Communication Enabler - 4511

• Programming display for 4225 frequency converter and other 4000 and 9000 devices
• Modbus RTU protocol interface over RS-485

Bluetooth Communication Enabler - 4512

• Display for system 4000 and 9000 devices
• iOS & Android compatible Bluetooth version 4.2/4.1/4.0
• Mounting in Zone 2 / Div. 2

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