DC Isolators

Wici LogoDC Isolators

Provide galvanically isolated DC Output proportional to DC Input

Wilkerson Instrument Co.     800-234-1343 Wilkerson Instrument Co Blog Page   Wilkerson Instrument Co LinkedIn Page

Isolators are used to break ground loops and to measure signals with high common mode voltages.

Ground loops are created when the source of a signal and the driven instrument have their common inputs tied to the earth at each device or the common lead is used to carry AC current for some other device.  AC current flowing in the common lead drops a small AC voltage due to the wire resistance. The voltage appears in series with the desired signal and creates “noise” on the desired signal.  The Isolator breaks the common lead and the AC current can no longer flow.

A common mode voltage is a voltage that is connected to the + and – inputs of a device.  Example – A small resistor in series with the + lead of a 138VDC battery and the – side of the battery is the “common” lead for the system.  The resistor drops a small voltage proportional to the battery current.  The Isolator can measure the small voltage across the resistor even though it is floating 138VDC above the system circuit common.

MM4380A Field Rangeable DC-DC Isolator Picture

Mighty Module Series Logo Series

MM4380A Field Rangeable Input and Output
Span ± 16mV to ± 256VDC, ± 0.8mA to ± 100mA
Offset Cancel ±110% of Span
MM4300 Factory Ranged Input and Output
Span ± 50mV to ± 250VDC, ± 1mA to ± 1ADC
MM4300A Four Models, Combinations of 4/20mA and 0/10VDC Input and Output
Mighty Module DC-DC Isolator Picture

UL/cUL Recognized
MM4380A and MM4300

DinMod Series Field Rangeable DC-DC Isolator Picture

DIN-MOD Series Logo Series

DM4380A Field Rangeable Input and Output
Span ± 16mV to ± 256VDC, ± 0.8mA to ± 100mA
Offset Cancel ± 110% of Span
DM4300A Four Models, Combinations of 4/20mA and 0/10VDC Input and Output
DM4391 Loop Powered Isolator
4/20 mADC In and Out
Linearized ± 0.02% of Span

UL/cUL Recognized
DM4380A and DM4300A

DR Series DC-DC Isolator Picture DR Series Logo

DR4380A Field Rangeable Input and Output
Span ± 50mV to ± 256VDC, ± 1mA to ± 100mA
DR4300 Factory Ranged Input and Output
Span ± 50mV to ± 250VDC, ± 1mA to ± 250mADC

Inputs: 1/5, 0/10VDC; 0/1, 4/20, 0/20, 0/50mADC
Outputs: Dual Isolated 4/20mADC


UL/cUL Recognized

Silver Series DC Isolated Two-Wire Transmitter Picture

50 mm Diameter

Silver Series Logo

SR2101 Isolated 2 Wire Transmitter, Head or DIN Rail Mount
Factory Ranged Input ± 16mV to ± 128 VDC, ± 0.01mA to ± 100mADC
30th Anniversary Banner

Wilkerson Instrument celebrates 32 years experience designing, manufacturing, distributing, and providing engineering help for the process control industries.

Phone always answered by a live person

Other Products:

  • Wireless Data Acquisition and Control
  • Loop Powered Displays
  • DC Motor Drives
  • DC Isolation
  • Frequency Inputs
  • Turbine Flow Meters


Industries Served:

  • Water and Waste Water
  • Power Generation
  • Bottling and Food Processing
  • Transportation
  • Chemical Processing
  • (OEM) Original Equipment Manufacturer

Wilkerson Instrument Company Inc.
2915 Parkway Street
Lakeland, FL. 33811 U.S.A

Wilkerson Instrument Co Blog Page   Wilkerson Instrument Co LinkedIn Page

800-234-1343    863-647-2000

Dataline Surge Protection Overview


Copyright © 2011 Citel Inc. USA, Used with permission

Data Line Surge Protection Overview


Telecommunication and data transmission devices (PBX, modems, data terminals, sensors, etc…) are increasingly more vulnerable to lightning induced voltage surges. They have become more sensitive, complex and have an increased vulnerability to induced surges due to their possible connection across several different networks. These devices are critical to a company’s communications and information processing. As such, it is prudent to insure them against these potentially costly and disruptive events. A data line surge protector installed in-line, directly in front of a sensitive piece of equipment will increase their useful life and maintain the continuity of the flow of your information.

Technology of Surge Protectors

All Citel telephone and data line surge protectors are based on a reliable multistage hybrid circuit that combines heavy duty Gas Discharge Tubes (GDTs) and fast responding Silicon  Avalanche Diodes (SADs). This type of circuit provides,

• 5kA Nominal Discharge Current (15 times without destruction per IEC 61643)
• Less than 1 nanosecond response times
• Fail-safe disconnection system
• Low capacitance design minimizes signal loss

Parameters for Selecting A Surge Protector

To select the correct surge protector for your installation, keep the following in mind :

• Nominal and Maximum Line Voltages
• Maximum Line Current
• Number of Lines
• Data Transmission Speed
• Type of Connector (Screw Terminal, RJ, ATT110, QC66)
• Mounting (Din Rail, Surface Mount)


To be effective, the surge protector must be installed in accordance with the following principles.

• The ground point of the surge protector and of the protected equipment must be bonded.
• The protection is installed at the service entrance of the installation to divert impulse current as soon as possible.
• The surge protector must be installed in close proximity, less than 90 feet or 30 meters) to protected equipment. If this rule cannot be followed, secondary surge protectors must be installed near to the equipment.
• The grounding conductor (between the earth output of the protector and the installation bonding circuit) must be as short as possible (less than 1.5 feet or 0.50 meters) and have a cross sectional area of at least 2.5 mm squared.
• The earth resistance must adhere to the local electrical code. No special earthing is necessary.
• Protected and unprotected cables must be kept well apart to limit coupling.


Test Standards and installation recommendations for communication line surge protectors must comply with the following standards :

• UL497B : Protectors for Data Communications and Fire-Alarm Circuits
• IEC 61643-21 : Tests of Surge Protectors for Communication Lines
• IEC 61643-22 ; Choice/Installation of Surge Protectors for Communication Lines
• NF EN 61643-21 : Tests of Surge Protectors for Communication Lines
• Guide UTE C15-443 : Choice/Installation of Surge Protectors

Special Conditions : Lightning Protection Systems

If the structure to be protected is equipped with a LPS (Lightning Protection System), the surge protectors for telecom or data lines that are installed at the buildings service entrance need to be tested to a direct lightning impulse 10/350us wave form with a minimum surge current of 2.5kA (D1 category test IEC-61643-21).

For a pdf copy of this post click here.


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