Resistors

 

 

Within TT Electronics’ resistors business unit are multiple manufacturing facilities and dedicated engineering teams providing custom solutions.

BI Technologies, IRC and Welwyn are market leading brands within this group, each with a track record in resistive component innovation of over seventy years.

TT Electronics offers the full spectrum of resistor technologies and a broad standard product range, in addition to providing custom engineered solutions.

 

 

The TT Electronics Resistors Business Unit strives to be the leading supplier of design-led, application specific resistors in the industrial, aerospace & defence and medical markets. In order to achieve this goal, we believe that we must gain our customers' confidence by becoming a trusted partner through all phases of the design, prototyping and manufacturing process in the application areas that matter most to our customers: circuit protection, detection, power management and signal conditioning. Our engineering teams, based at Corpus Christi, Texas in the USA and at Bedlington in the UK, are supported by a global network of FAE, sales and customer service teams.

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Sales Offices

 
Region Address Telephone

Americas

TT Electronics,
4222 South Staples Street,
Corpus Christi, TX 78411, USA
+1 361-992-7900

Asia

TT Electronics, 
514 Chai Chee Lane, 
#02-10A Bedok Industrial Estate, Singapore 469029
+65 6444 5667

Europe (EMEA)

TT Electronics,
Welwyn Electronics Park,
Bedlington, Northumberland,
NE22 7AA, UK
+44 (0)1670 822181
 

Sales Enquiry

 

Franchised Distributors

Americas

Allied ex-en.alliedelec.com
Arrow www.arrownac.com
Falcon Electronics www.falconelec.com
Future www.futureelectronics.com
Hughes Peters www.hughespeters.com
Justin www.justinelectronics.com
Mouser www.mouser.com
Newark Element 14 www.newark.com
Projections Unlimited (PUI) www.gopui.com
Sager www.sager.com
TTI www.ttiinc.com
Walker Components www.walkercomponent.com
WPG/I Americas www.wpgamericas.com

Asia

Arrow components-asiapac.arrow.com
Chinamax www.chinamax.com.hk
Dragon www.dragonipt.com
Element 14 www.farnell.com
Future www.futureelectronics.com
Maxmega www.maxmega.com
Mouser www.mouser.com
Sakae Electronics www.sakae-denshi.com
Sea Union www.seaunionweb.com.tw
Seamax www.seamax.com.sg
Serial www.serialsystem.com
Shenzhen Deruitai www.deruitai.com
SM Technologies www.smetgroup.com
TTI www.ttiasia.com
WPG/I Asia www.wpgholdings.com
Yongjun Electronic Co. www.yongjun.co.kr

Europe (EMEA)

Acte vanpee.se
Arrow www.arroweurope.com
Bürklin www.buerklin.com
Charcroft www.charcroft.com
Distrelec www.distrelec.com
Dreyer www.dreyer-elektronik.de
Elcart www.elcart.com
Elfa www.elfa.se
Future www.futureelectronics.com
Gateway www.gatewaycando.com
Gudeco www.gudeco.de
Mouser www.mouser.com
Phoenix www.phnx.co.il
PK Components www.pk-components.de
PNE www.pne.fr
Farnell Element 14 www.farnell.com
Radiant www.radiant.su
Sorelec www.sorelec.com
TTI www.ttieurope.com/page/branch-locator
Vibratec www.vibratec.ch
 

Manufacturer’s Representatives (Americas)

 
ME, VT, MA, RI, CT Coakley Boyd and Abbett www.cbane.com
FL Conley and Associates www.conleyrep.com
Southern CA Astron Electronics www.astron1.com
MI, Western PA, IN, KY, OH, WV, TN, MS, AL, GA, MX R. O. Whitesell and Associates www.whitesell.com
ND, SD, MN Electric Component Sales www.ecs-sales.com
 

Manufacturer’s Representatives (Asia)

 

South Korea

VD Components www.vd-components.com

The formulae in these tools are believed to be correct but they are provided for guidance only and no liability is accepted for consequences of errors.

Resistance Calculator

The choice of resistance value can determine the magnitude of voltage, current and power dissipated in a circuit.

The resistance value of a resistor is defined as the ratio of the voltage across it to the current through it. The power dissipated is the product of voltage and current. In this calculator, enter any two known values, and the remaining two values are calculated.




 

Limiting Factor Calculator

Resistors have two ratings related to electrical stress. The main one is Rated Power (Pr) in Watts. This is the maximum power the resistor can continuously dissipate at a stated ambient temperature (usually 70°C). If this is exceeded, the resistor will get too hot. Possible results of this are permanent value change, open circuit failure, and damage to the PCB or surrounding components.

The second rating is Limiting Element Voltage (LEV) (sometimes called Voltage Rating or Operating Voltage) in Volts. This is the maximum voltage that can be continuously applied across the resistor, even if Rated Power is not being reached. Applying a higher voltage may result in electrical breakdown. Possible results of this are permanent value change and open circuit failure.

In almost every case where a specific type and value is selected, only one of these ratings will be relevant. This rating is the limiting factor, and which it is can be determined using the calculator.

Limiting Element Voltage Diagram

Below the Critical Resistance the Rated Power is the limiting factor whilst above it the Limiting Element Voltage is the limiting Factor



Conclusion:

Temperature Derating Calculator

Resistors must be operated at lower dissipations when at high ambient air temperatures.

The power rating given for resistors applies only up to a certain ambient air temperature. This is normally 70°C or 25°C, but 40°C, 85°C and other temperatures are sometimes used. At local air temperatures above this rating air temperature the permitted power dissipation reduces, until at the maximum ambient air temperature only nominal dissipation is allowed. This prevents excessive temperature rise in the resistor body and / or solder joints.

The derating characteristic is normally linear from rated power down to 0W. The calculator performs two functions. Firstly, given the operating air temperature it gives the maximum permitted power dissipation. Secondly, given the operating power dissipation it gives the maximum permitted ambient air temperature.

Limiting Element Voltage Diagram

Either


Or leave blank and enter below

 

Capacitor Discharge Calculator

Bleed resistors are used to discharge capacitors to safe voltage levels after power is removed.

A bleed resistor may be either switched across the capacitor for rapid discharge without quiescent dissipation, or permanently connected for high reliability and low cost. In the latter case there is a tradeoff between the time to reach safe discharge and the quiescent power loss.

Selecting a suitable ohmic value is made easier by the calculator. This links the discharge time to the resistor value and calculates the initial power. For a switched bleeder this is the peak power with decay time constant indicated. For a permanently connected bleeder it is the continuous dissipation, and the resistor chosen must be rated accordingly.

Limiting Element Voltage Diagram






 

Pulse Calculator

The pulse performance of resistors is important in inrush, protection and discharge applications.

The way in which this performance is presented depends upon resistor technology. Wirewound resistors have an energy capacity in Joules which depends on ohmic value, but not on short pulse duration. Thick and thin film resistors have a peak power depending on pulse duration. However, the energy capacity is not fixed and there is less dependence on ohmic value.

In order to relate the pulses experienced in an application to the pulse performance stated on the datasheet, it is necessary to calculate peak power for film or energy for wirewound. Common exponential pulse shapes must be converted to rectangular pulses of equivalent energy as rectangular pulses are generally used to characterise resistor performance. Finally, if pulses are continuous, the mean power dissipation must be calculated so as to ensure that the power rating is not exceeded.

Single Pulse

Resistor:

A single pulse condition relates to pulses which are sufficiently infrequent as to make mean power negligible. In other words, the resistor cools completely to ambient temperature between successive pulses.

Pulse Amplitude:

Limiting Element Voltage Diagram
Or leave blank and enter below

Pulse Length:

Or leave blank and enter below
Or leave blank and enter below:



 

Continuous Pulse

Resistor:

A continuous pulse condition relates to pulses which are repeated sufficiently frequently to give cumulative heating. In this case the mean power dissipation must be kept below the resistor power rating.

Continuous Background Dissipation

Limiting Element Voltage Diagram
Or leave blank and enter below

Pulse Amplitude

Or leave blank and enter below

Pulse Length

Or leave blank and enter below
Or leave blank and enter below

Pulse Frequency

Or leave blank and enter below





 

 

Technical Query | Sample Request | Customer Service| Sales Enquiry

Customer Service Support

 
Region Address Telephone
Americas TT Electronics,
Welwyn Electronics Park,
Bedlington, Northumberland,
NE22 7AA, UK
+44 (0)1670 822181
For customer service support on ITAR / Export Control sensitive products, please use the USA based sales office contact.
Asia TT Electronics, 
514 Chai Chee Lane, 
#02-10A Bedok Industrial Estate, Singapore 469029
+65 6444 5667
Europe (EMEA) TT Electronics,
Welwyn Electronics Park,
Bedlington, Northumberland,
NE22 7AA, UK
+44 (0)1670 822181
 

Key Resistors Site Locations

Corpus Christi: TT Electronics, 4222 South Staples Street, Corpus Christi, TX 78411, USA 
CAGE Code 57027

 

Bedlington: TT Electronics, Welwyn Electronics Park, Bedlington, Northumberland, NE22 7AA, UK 
CAGE Code U1395

 

 

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