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SM186-4 2.5 Watt Wire Wound 4-Terminal Resistor
SM186-4 2.5 Watt Wire Wound 4-Terminal Resistor 

Electrical & Physical Specifications:

A-Length: 16.50mm (.650")
B-Diameter: 6.35mm (.250")
Lead Dimensions: .0285" dia. X 1.400" long (min.)
Min Res. @ Max Power: .025Ω @ 2.5W
Min Res. @ Derated Power: .001Ω @ .1W
Temperature Range: -55°C to +275°C










SM-4 Series Engineering Attributes:

RESISTANCE & TOLERANCE
Standard: Any Ohmic value or decimal part of an Ohm desired from .015Ω to 100Ω with tolerances to ±.005%

Special: From .001Ω to .015Ω with tolerances to ±.1%
Refer to Fig. 6 for min. resistance vs. tolerance ratios.


TCR CHARACTERISTICS
Standard: 0±15 PPM/°C.

Special: 0±10 PPM/°C.
Please specify temperature span of operation.


STABILITY VS. TIME
To ±.001%/year @ +25°C. (No Load)


PROTECTIVE COATING SEAL
Solvent resistant coat with indelible marking


POWER RATING
The standard minimum resistance at full power is based upon ±1% resistance tolerance @ +25°C. Derating is required for lower values, closer tolerances, and higher temperatures. Please refer to the Derating Table shown here & Fig. 5 below.

*Type SM-4 Derating Table:
 
For ±1% Res. tol. apply up to 100% of rated power at +25°C. derated to zero at +275°C.
For ±0.5% Res. tol. apply up to 80% of rated power at +25°C. derated to zero at +225°C
For ±0.25% Res. tol. apply up to 60% of rated power at +25°C.derated to zero at +175°C.
For ±0.1% Res. tol. apply up to 40% of rated power at +25°C. derated to zero at +125°C.
For ±0.05% Res. tol. apply up to 20% of rated power at +25°C. derated to zero at +75°C.
 
* Percent of Rated Power vs. Combined Temp. of Self-Heating and Ambient in Degrees Celsius.

TWO (2) TERMINAL VS. FOUR (4) TERMINAL (Kelvin)
Two terminal resistors are generally used for high Ohmic values, where the effects of lead-out resistance and contact resistance are minimal. Allow approximately ±.001% of an Ohm per inch, for the lead-out resistance on two terminal designs. However, on low values where lead resistance can be a part of a very accurate measurement, the adder may be eliminated by using a 4-terminal device, because 4 terminal circuits will only be indicate the voltage drop across the resistor.
FOUR TERMINALS
PRC's type SM-4 has four solderable hot-tinned copper leads. Lead identification is academic because of its single joint construction. To observe uniformity, while observing the PRC marking on the body of the resistor, select the 2 leads closest to the top for sense leads & use the remaining two for current leads.


CAN'T FIND THE PART TO MATCH YOUR SPECS?

Then let PRC custom manufacture your wire wound resistor, sensor, or shunt with some of the shortest lead times in the industry. Engineering samples can be supplied at no cost to you in 7-10 days for most jobs. Computer tracking charts are available for reference with certain part types. If you need a specific marking on your part(s) we will custom print your order with the marking you desire & at no additional cost to you. If needed, you can interchange the size, shape, lead dimension, wattage, voltage, current, Ω value, tolerance, & TCR characteristics with most part types. Visit our SM 4-Terminal Series & see if one of our other parts from the same series will satisfy all your requirements. If you still do not find a part that meets the exact specifications your application requires, simply click Contact/Request For Quote & fill in all known spec fields. One of our highly trained engineers will review your objectives and see if we can modify one of our standard parts to satisfy all your requirements. If you are unsure how to accurately complete this form, give us a call & our sales department will be happy to assist you.

ORDERING PROCEDURE

Our sales department is available to provide price, delivery, lead time & all other pertinent ordering instructions to companies within the U.S.A. If you wish to place an order in the United States, simply give us a call & ask for the Sales Department, our contact information is at the very top of every page. For companies outside the U.S.A., we have sales representatives in over 30 different countries to assist you. Click the link International Sales Representative Map to locate the sales representative nearest to your region & view their contact information. Our international sales representatives are readily available & eager to answer all inquiries regarding pricing, lead time, & ordering instructions as well as any other questions you may have. Our site also features a Virtual Store stocked with many popular sizes from our HR axial lead series and our world renown LVS3 surface mounted shunt. Our unique PRC100 series that tracks like platinum at a fraction of the cost can also be found inside. In addition to these items there are several different designs from our most sought after part types in our premium wire wound product line inside, all waiting to be shipped today to meet your critical deadlines. Small quantities up to twenty-five pieces of each product type with selected Ohmic values & tolerances available. Once inside the virtual store you can instantly purchase parts using your Visa or MasterCard & choose from 4 levels of shipping services, including next day delivery, all delivered by UPS. Feel free to browse through our store anytime day or night & check out what's in stock from the comfort & privacy of your own computer. The store is open 24 hours a day for your convenience.

Detailed Images
Derating Information

Derating Information




Minimum Resistance vs. Tolerance

Minimum Resistance vs. Tolerance




 

Details
 
SKU SM186-4
Type 4-Terminal Axial
Length 16.50mm (.650")
Lead Dimensions .0285" dia. X 1.400" long (min.)
Diameter 6.35mm (.250")
TCR Char. 0±15ppm/°C (between +25°C. and +100°C.)
Temperature -65°C. to +275°C.
Resistance .001Ω to 100Ω
Tolerance to ±.005%
Max Amps 10
Stability to ±.001% per year at +25°C
Max Watts 2.5
Amps 10
Special Resistance .001Ω @ .1W to .025Ω @ 2.5W
Lead Free Yes



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