element14 Community
element14 Community
    Register Log In
  • Site
  • Search
  • Log In Register
  • About Us
  • Community Hub
    Community Hub
    • What's New on element14
    • Feedback and Support
    • Benefits of Membership
    • Personal Blogs
    • Members Area
    • Achievement Levels
  • Learn
    Learn
    • Ask an Expert
    • eBooks
    • element14 presents
    • Learning Center
    • Tech Spotlight
    • STEM Academy
    • Webinars, Training and Events
    • Learning Groups
  • Technologies
    Technologies
    • 3D Printing
    • FPGA
    • Industrial Automation
    • Internet of Things
    • Power & Energy
    • Sensors
    • Technology Groups
  • Challenges & Projects
    Challenges & Projects
    • Design Challenges
    • element14 presents Projects
    • Project14
    • Arduino Projects
    • Raspberry Pi Projects
    • Project Groups
  • Products
    Products
    • Arduino
    • Avnet Boards Community
    • Dev Tools
    • Manufacturers
    • Multicomp Pro
    • Product Groups
    • Raspberry Pi
    • RoadTests & Reviews
  • Store
    Store
    • Visit Your Store
    • Choose another store...
      • Europe
      •  Austria (German)
      •  Belgium (Dutch, French)
      •  Bulgaria (Bulgarian)
      •  Czech Republic (Czech)
      •  Denmark (Danish)
      •  Estonia (Estonian)
      •  Finland (Finnish)
      •  France (French)
      •  Germany (German)
      •  Hungary (Hungarian)
      •  Ireland
      •  Israel
      •  Italy (Italian)
      •  Latvia (Latvian)
      •  
      •  Lithuania (Lithuanian)
      •  Netherlands (Dutch)
      •  Norway (Norwegian)
      •  Poland (Polish)
      •  Portugal (Portuguese)
      •  Romania (Romanian)
      •  Russia (Russian)
      •  Slovakia (Slovak)
      •  Slovenia (Slovenian)
      •  Spain (Spanish)
      •  Sweden (Swedish)
      •  Switzerland(German, French)
      •  Turkey (Turkish)
      •  United Kingdom
      • Asia Pacific
      •  Australia
      •  China
      •  Hong Kong
      •  India
      •  Korea (Korean)
      •  Malaysia
      •  New Zealand
      •  Philippines
      •  Singapore
      •  Taiwan
      •  Thailand (Thai)
      • Americas
      •  Brazil (Portuguese)
      •  Canada
      •  Mexico (Spanish)
      •  United States
      Can't find the country/region you're looking for? Visit our export site or find a local distributor.
  • Translate
  • Profile
  • Settings
TDK
  • Products
  • Manufacturers
  • TDK
  • More
  • Cancel
TDK
Documents Power Supply "Remote Sense" Mistakes and Remedies
  • Blog
  • Forum
  • Documents
  • Events
  • Polls
  • Members
  • Mentions
  • Sub-Groups
  • Tags
  • More
  • Cancel
  • New
Join TDK to participate - click to join for free!
Actions
  • Share
  • More
  • Cancel
Engagement
  • Author Author: Nortski
  • Date Created: 9 Oct 2013 6:14 PM Date Created
  • Last Updated Last Updated: 8 Oct 2021 5:43 AM
  • Views 1063 views
  • Likes 0 likes
  • Comments 0 comments
Related
Recommended

Power Supply "Remote Sense" Mistakes and Remedies

Most medium to high power AC-DC power supplies and some DC-DC converters include "Remote Sense" connection points (+ and - Sense) that are used to tightly regulate the supply's output voltage at the load. Since the output cables that connect a power supply's output to its load have some resistance, as current flow increases, so will the voltage drop across the cables (I x R = Voltage Drop). Moreover, since it's best to regulate the voltage directly at the load, the use of the two Remote Sense wires connected from the supply to the load will compensate for these unwanted voltage drops. Refer to Fig. 1 which shows the typical connections when the Remote Sense function is used.



image

Fig. 1: Power Supply with Twisted "Remote Sense" Wires Connected to the Load


Typical "Remote Sense" Problems & Remedies


  1. Most remote sensing circuits are capable of compensating for from 0.25V to 0.75V of voltage-drops across the output cables. However, to be sure, always check your power supply's instruction manual to determine its maximum remote sense compensating range. If the voltage drop across the output cables exceeds the compensating range of the remote sense circuits, the voltage at the load will no longer be regulated. This problem can be remedied by either reducing the length of the output cables or increasing the size (heavier wire gauge) of the output cable's to reduce the excessive voltage drop. Voltage drops across the output cables should be minimized since this is a source of wasted power. For example, with just a 0.5V cable drop with a 100A load, the lost power amounts to 50W in each cable or 100W total.
  2. The remote sense function automatically increases the output voltage at the output terminals of the supply to compensate for any unwanted voltage drop in the output cables with heavy load currents. Likewise, the remote sense function decreases the output voltage of the supply when the required load current is reduced. In some applications, the power supply's output needs to be adjusted by the user to voltage higher than its nominal (e.g. 5V nominal, adjusted to 5.5V). Always adjust the power supply's output while measuring the voltage at the load. In addition, care should be taken to assure that under full load that the remote sense function does not push the Vout to a higher voltage that could possibly trip the OVP set-point and shutdown the supply. Therefore, always read the power supply's instruction manual to be aware of the supply's adjustment range and OVP set-point.
  3. The remote sense leads carry very little current so light gauge wires can be used. However, steps should be taken to ensure that the remote sense wires do not pick up radiated noise by either twisting the + and - Sense wires together and/or by shielding the wires from the noise (refer to Fig 1). It is best to use different colored sense wires (e.g., black and red) so that after they are twisted it is easy to determine which wire is the + and – Sense.
  4. Refer to Fig. 2 below for a simplified schematic of a power supply's remote sense circuits. It is important to observe the correct polarities, i.e., the +Sense wire should connect at the load near the +Vload connection and the –Sense wire should connect at the load near to the – Vload connection. If by mistake the remote sense wires are crossed-connected (+Sense to –Vload and – Sense to +Vload) current will flow in the Sense lines and burn out the internal Rsense resistors, causing a malfunction of the supply. Typically, these internal Rsense resistors are around 10 to 100 Ohms with a maximum rating of 0.5W.

 

imageFig. 2: Simplified Schematic of Remote Sense Circuit with External Output & Sense Wires

 


  1. We have seen applications where the user has installed a switch or fuse in series with one or both output wires. This can cause a serious problem if the remote sense lines remain connected to the load, because if the output cable switch or fuse opens, current will flow in the sense lines and cause the internal Rsense resistors to burn up. System debugging can cause similar problems, for example, where the power and sense cables are located on separate connectors and if by error, only the power cable connector is disconnected.
  2. There are applications where the user may not want to use the remote sense feature. In these cases, the remote sense lines should not be left open for optimum load regulation; instead, a local sense configuration must be used. Referring to Fig. 3, to use a local sense set up the + and -Sense lines should be connected to either their corresponding local sense (LS) terminals, which are provided on many power supplies, or connected to the corresponding +Vout and –Vout terminals. Most power supplies are shipped from the factory with these "Local Sense" jumpers installed on the power supply (see photos below).

image

Fig. 3: Schematic of Power Supply with "Local Sense" Jumpers Installed


image

Photo of Power Supply with Local Sense Wires Connected (see Red & Black jumper wires)


image

Photo of PSU with Sense Screw Terminals Connected to Output Screw Terminals with Metal Jumpers

In summary, the "Remote Sense" feature automatically compensates for unwanted output cable drops, which vary as the output current increases and decreases. This feature is advantageous to the user, but is subject to mistakes that should be avoided to insure the proper operation of the power supply and the end-product.

  • Share
  • History
  • More
  • Cancel
  • Sign in to reply
element14 Community

element14 is the first online community specifically for engineers. Connect with your peers and get expert answers to your questions.

  • Members
  • Learn
  • Technologies
  • Challenges & Projects
  • Products
  • Store
  • About Us
  • Feedback & Support
  • FAQs
  • Terms of Use
  • Privacy Policy
  • Legal and Copyright Notices
  • Sitemap
  • Cookies

An Avnet Company © 2025 Premier Farnell Limited. All Rights Reserved.

Premier Farnell Ltd, registered in England and Wales (no 00876412), registered office: Farnell House, Forge Lane, Leeds LS12 2NE.

ICP 备案号 10220084.

Follow element14

  • X
  • Facebook
  • linkedin
  • YouTube