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Highest Rated, Broadest Range of Inrush Current

Highest Rated, Broadest Range of Inrush Current

TRANSFORMER PROTECTION FROM – USE AN NTC THERMISTOR DELIVERING HIGH-QUALITY INRUSH CURRENT PROBLEM STATEMENT LIMITING PRODUCTS & SOLUTIONS A draws inrush current that can exceed saturation current affecting the magnetic property of the core. This happens even if the transformer is on no load Since 1994, Ametherm has provided the most reliable and effective inrush with its secondary open. The magnitude of the inrush current depends on the solutions available. We deliver on that promise through instant on the AC wave at which the transformer is switched on. If the instant innovative design, quality manufacturing, and exceptional customer support. happens to be such that the AC voltage wave is going through its peak value, then there will be no inrush current drawn by the transformer. The magnitude of the • Broadest range of inrush current limiting power thermistors available current in this case will be at normal no load value. If the instant happens to be • Experienced engineering team to help you find the best solutions such that the AC wave is going through its zero value, then the current drawn will • Durable products that are UL and CSA approved, and RoHS compliant be very high that exceeds the saturation current (see Figure 1). In this scenario, the • ISO:9001:2008 certified manufacturing processes transformer has to be protected from inrush current. • Free samples shipped quickly for testing and evaluation • Short lead times to meet your production demands PROTECTION OF THE TRANSFORMER • Competitive prices on long-lasting, reliable products This application note provides a convenient solution (see Figure 2) to Figure 1 deal with the problem of inrush current exceeding saturation current in Contact us today for more information . The solution uses NTC Thermistor in series with the or to order your free samples. primary. This NTC Thermistor offers high resistance at the beginning of switching and limits the inrush current. After a short time, the NTC ALSO AVAILABLE THROUGH: Thermistor resistance decreases to a low value due to self heating and INTERNATIONAL HIGHEST RATED, does not affect normal operation. Digi-Key www.digikey.com Newark www.newark.com Each transformer rating: 1000 VA, Each transformer step-down: 30 V EUROPE Total transformer rating: 2000 VA T: 800-808-2434 Thomatronik www.thomatronik.de BROADEST RANGE OF Filter used: 30V, 2300 µF 775-884-2434 UNITED KINGDOM (Outside the US and Canada) Rhopoint Components www.rhopointcomponents.com NTC SELECTION CRITERIA: ENERGY F: 775-884-0670 CHINA INRUSH CURRENT LIMITERS 1 2 www.ametherm.com IBS Electronics www.ibselectronics.com Energy required for the NTC: 2 LI [email protected] Inductive reactance of the transformer Input Voltage 120 V MALAYSIA XL = = = 0.213Ω Inrush Current 564 A Figure 2 IC Resource www.icresource.com.sg Note: 3111 N. Deer Run Road Peak Inrush Current occurs in one cycle = 564 A, as measured on the oscilloscope For a complete list of Ametherm distributors, Input Voltage = 120 VAC Carson City, Nevada 89701 USA please visit www.ametherm.com Frequency = 60 Hz 100

XL = 2 π f L = 2 x 3.14 x 60 x L, Calculate Inductance L Yields 80 Percent L = 565 µH of Rated 60 Imax Energy rating for the NTC = 1 2 = 1 (565 x 10 –6) (564)2 = 90 Joule 2 LI 2 40

NTC SELECTION CRITERIA: STEADY STATE CURRENT 20

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Assume, Efficiency of transformer: 90%, Ambient : 85 = -50 -40 -25 0 25 50 65 75 100 125 150 KVA of Transformer Ambient Temperature I steady = Degrees Centigrade (C ) (Efficiency of Transformer)x(Minimum Input Voltage) (2.0 KVA) HIGHEST RATED, BROADESTProtect your sensitive RANGE electronic OF INRUSH CURRENT LIMITERS For this transformer, I steady is calculated as = = 31.75 A (0.70) x (90 V) Figure 3 components from damaging surge Normally Thermistors are rated up to 65ºC for their operating current, and then a For Power Supplies with Protect your sensitive electronic components from damaging surge derating factor must be taken in to account. You can use any of the NTC currents that can occur when electrical currents that can occur when electrical circuits are switched on. Thermistors that are rated up to circuits are switched on. Ametherm’s Decision criteria: choose an NTC Thermistor that can provide at least the steady state Outputs from 50 to 7,500 watts 36.0 A to meet your Steady State Ametherm’s durable, highly-rated inrush current limiters are designed to current as calculated above: durable, highly-rated inrush current Current and Energy Requirements. and 1.0 To 50 AMPs SSI effectively control damaging surges in a wide range of applications. Using the de-rating curve (see Figure 3) at 80, use 90% of max rated steady state current See the charts for part numbers. limiters are designed to effectively = 0.9 x 36 A = 32.40 A control damaging surges in a wide 800-808-2434 •range www.ametherm.com of applications. T: 800-808-2434 : 775-884-2434 (Outside the United States and Canada) : www.ametherm.com : [email protected] DESIGN TIPS FOR INRUSH CURRENT LIMITERS MOUNTING INRUSH CURRENT LIMITERS

The SL22 series of inrush current limiters is CSA & UL approved, and other SL series Inrush current limiters may get hot in operation. parts are CSA approved. Refer to the following guidelines when using these designs. For best results, use the following guidelines: 1. The body should not touch other components on the PCB. • Do not place on the PCB near temperature 2. A rated at the maximum current rating of the device (allowing for any sensitive components. derating that may be needed for ambient in excess of 65°C) or • Use a high temperature solder on the PCB. Protection. lower than the maximum current rating of the 7.87 mm device should be used. • If equipped, use a spacer to stand off the surge gard from the PCB or PROTECTING YOUR ELECTRONIC COMPONENTS contact us for pre-formed devices. WITH INRUSH CURRENT LIMITERS • Keep away from wiring looms.

INRUSH CURRENT LIMITERS INRUSH CURRENT LIMITERS BIG AMP INRUSH CURRENT LIMITERS MEGA SURGE CURRENT LIMITERS Imax. Max Rimax Jmax Energy Tmax (mm) Steady State Resistance Resistance at Rating Vmax Dmax (mm) Max Inrush current limiters are power NTC Imax. Max Rimax Jmax Energy Tmax (mm) Part Current at 25°C Resistance Max Current (Joules) Voltage Max Dia. Thickness Lead Dia. Steady State Resistance Resistance at Rating Vmax Dmax (mm) Max Imax. Max Jmax Energy Resistance Resistance Resistance Number (Amperes) () Tolerance % (ohms) (Ws) Rating Over Coating Over Coating (mm) Part Current at 25°C Resistance Max Current (Joules) Voltage Max Dia. Thickness Lead Dia. Steady State Resistance Rating Vmax at 100% SS at 75% SS at 50% SS thermistors manufactured from a Number (Amperes) (ohms) Tolerance % (ohms) (Ws) Rating Over Coating Over Coating (mm) Part Current at 25°C Resistance (Joules) Voltage Max Cap @ Current Current Current SL03 10001 1 10.0 20 0.80 2.0 120 3.0 3.0 0.5 Number (Amperes) (ohms) Tolerance % (Ws) Rating Max V uF (ohms) (ohms) (ohms) SL03 22101 1 220.0 20 2.20 2.0 120 3.5 3.5 0.5 SL22 12103 3 120 25 0.9 80 265 22 6.0 1.0 specially-formulated metal MS12 15102 2 150 25 110 440 560 1.05 1.9 2.71 SL05 5R001 1 5.0 25 0.80 5.0 120 6.0 3.5 0.5 SL22 50004 4 50 20 0.44 80 265 22 6.0 1.0 MS22 12103 3 120 25 220 440 1100 1.2 1.4 2.5 SL05 60001 1 60.0 20 0.82 3.0 120 6.0 4.5 0.5 ceramic material that is capable of SL22 30005 5 30 20 0.4 80 265 22 6.0 1.0 MS22 22103 3 220 25 75 265 580 1.4 1.67 3 SL05 12101 1 120.0 20 1.40 1.5 120 6.0 4.5 0.5 SL22 14007 7 14 25 0.12 75 265 22 6.0 1.0 Features suppressing high inrush current surges. MS15 66003 3.5 66 25 125 440 600 0.4 0.824 1.73 SL08 10002 2 10.0 20 0.29 9.0 240 8.8 4.5 0.5 SL22 10008 8 10 20 0.095 90 265 22 6.0 1.0 MS15 40004 4 40 25 135 440 700 0.4 0.623 0.96 • Up to 50A SSI SL08 33001 2 33.0 20 0.75 8.0 240 8.5 4.5 0.5 Connected in series with the load at SL22 2R510 10 2.5 20 0.04 90 265 22 6.0 1.0 MS22 50004 4 50 25 240 440 1200 0.4 0.625 1.1 SL08 50001 1.1 50.0 20 0.90 8.0 265 8.0 4.0 0.5 SL22 7R010 10 7 20 0.08 100 265 22 6.0 1.0 MS22 75004 4 75 25 240 440 1200 0.5 0.77 1.35 • 0.5 to 220 ohms SL08 12101 1 120.0 20 1.60 8.0 265 8.5 5.5 0.5 -on, the thermistor’s relatively SL22 0R712 12 0.7 20 0.03 120 265 22 6.0 1.0 MS22 20005 5 20 25 180 440 1000 0.32 0.5 0.72 SL08 10101 1 100.0 20 1.40 8.0 265 8.5 5.5 0.5 SL22 5R012 12 5 20 0.05 100 265 22 6.0 1.0 • Limits up to 900 Joules high cold resistance limits the current. MS32 20008 8 20 25 250 440 1250 0.2 0.33 0.9 SL22 4R014 14 4 20 0.05 100 265 22 6.0 1.0 MS35 20010 10 20 25 500 680 1000 0.3 0.4 0.5 of inrush energy SL22 2R515 15 2.5 20 0.03 90 265 22 6.0 1.0 MS32 10015 15 10 25 250 440 1250 0.06 0.1 0.19 Standard Inrush Current Limiters SL22 0R516 16 0.5 20 0.02 160 265 22 6.0 1.0 MS35 10018 18 10 25 500 680 1000 0.1 0.32 0.48 SL10 5R002 2 5.0 20 0.35 20 265 10.5 4.0 0.5 As the current flows, the thermistor SL22 2R018 18 2 20 0.037 90 265 22 6.0 1.0 MS32 5R020 20 5 25 300 440 1250 0.035 0.06 0.1 With energy ratings to 900J, SL12 5R002 2 5.0 20 0.30 25 265 12.0 6.0 0.8 SL22 1R020 20 1 20 0.015 65 265 22 6.0 1.0 heats, reducing its resistance value so MS32 2R025 25 2 25 300 440 1500 0.02 0.032 0.06 SL12 20002 2 20.0 20 0.45 30 265 12.5 5.1 0.8 SL32 0R230 30 0.25 25 0.010 100 265 32 6.0 1.0 Megasurge inrush current limiters Big Amp inrush current MS35 5R025 25 5 25 600 680 1000 0.05 0.1 0.15 SL12 25002 2 25.0 20 0.55 30 265 12.5 5.1 0.8 that once the initial surge has been are suitable for very high power MS35 3R030 30 3 25 750 680 1250 0.03 0.052 0.08 SL15 22102 2 220.0 25 0.90 50 265 15.0 4.5 0.8 Imax. Max Resistance Resistance Resistance safely held off, the resistance in the limiters are high current, Steady State Resistance Jmax Energy at 100% SS at 70% SS at 50% SS MS35 2R035 35 2 25 750 680 1600 0.02 0.027 0.04 applications, such as: SL10 10003 3 10.0 15 0.26 17 265 10.0 4.0 0.5 Part Current at 25°C Resistance Rating Vmax Voltage Current Current Current MS32 1R036 36 1 25 300 440 1500 0.012 0.015 0.03 SL12 25003 3 25.0 20 0.35 30 265 12.5 5.1 0.8 high energy handling Number (Amperes) (ohms) Tolerance % (Joules) (Ws) Rating (ohms) (ohms) (ohms) • AC Motors circuit is held at a low value to maxi- MS35 1R040 40 1 25 800 680 1700 0.012 0.02 0.03 SL12 12103 3 120.0 20 0.48 25 265 12.0 5.0 0.8 SL32 10015 15 10 20 150 265 0.048 0.074 0.102 devices capable of MS35 0R550 50 0.5 25 900 680 2000 0.008 0.013 0.02 • Compressors SL12 5R004 4 5.0 15 0.15 25 265 12.5 5.1 0.8 mize efficiency. Applications include: SL32 5R020 20 5 20 200 265 0.034 0.056 0.082 SL15 7R004 4 7.0 20 0.10 55 265 15.5 5.0 0.8 absorbing up to 250Js and SL32 2R025 25 2 20 250 265 0.025 0.031 0.049 • Frequency Generators SL12 12004 4 12.0 20 0.22 40 265 12.5 6.0 0.8 SL32 0R530 30 0.5 20 150 265 0.011 0.019 0.058 • High Power Motor Controllers SL15 16004 4 16.0 20 0.25 50 265 15.0 5.2 0.8 • Power Supplies suitable for large switch SL32 1R030 30 1 20 160 265 0.014 0.018 0.048 SL15 40004 4 40.0 20 0.30 30 265 15.5 5.0 0.8 mode power supplies, SL32 1R036 36 1 20 160 265 0.01 0.015 0.028 • High Power Battery Chargers SL10 2R505 5 2.5 30 0.12 30 265 10.0 5.0 0.5 • Lighting Circuits Part Series D mm (Nom) T mm (Nom) Lead Dia. (mm) S mm (Nom) L mm (Nom) C mm (Nom) SL15 5R005 5 5.0 20 0.15 50 265 15.5 5.1 0.8 • Any Circuit Subject To UPSs, HVAC, and motor MS12 12.0 Nom 7.0 Nom 1.0 Nom 7.80 Nom 38.0 Nom 3.42 Nom • Motor Drives SL12 10005 5 10.0 20 0.13 40 265 12.5 5.1 0.8 Dmax (mm) Max Dia. Tmax (mm) Max Lead Spacing (mm) Length (mm) MS15 15.0 Nom 7.0 Nom 1.0 Nom 7.80 Nom 38.0 Nom 6.70 Nom SL12 10006 6 10.0 20 0.12 40 265 12.0 5.1 0.8 speed controllers. Over Coating Thickness Over Coating Lead Dia. (mm) Nominal Nominal • MRI Machines • Switch-On Current Surges MS22 22.0 Nom 8.5 Nom 1.0 Nom 7.80 Nom 38.0 Nom 3.82 Nom SL15 2R507 7 2.5 20 0.06 40 265 15.5 4.5 0.8 32 6 1.0 7.9 38 MS32 32.0 Nom 8.5 Nom 1.0 Nom 7.80 Nom 38.0 Nom 4.5 Nom • Plasma Cutting Tools SL15 5R007 7 5.0 20 0.09 50 265 15.0 5.0 0.8 • Electric Motors MS35 35.0 Nom 10 Nom 2.5 Nom 19.0 Nom 39.0 Nom 7.50 Nom SL15 4R008 8 4.0 20 0.07 40 265 15.0 4.5 0.8 • Protection • Power Supplies SL15 2R509 9 2.5 20 0.04 40 265 15.0 5.5 0.8 PART NUMBERING • Toroidal Transformers SL18 2R508 8 2.5 20 0.06 90.0 265 19.0 5.0 1.0 SL18 5R006 6 5.0 20 0.14 75.0 265 19.0 5.0 1.0 SL 10 100 04 up to 7.5 KVA SL18 10005 5 10.0 20 0.18 75.0 265 19.0 6.0 1.0 Steady state current • Welding Machines SL18 30006 6 30.0 25 0.17 75.0 265 19.0 6.0 1.0 Resistance at 25*C SL18 47003 3 47.0 25 0.13 75.0 265 19.0 6.0 1.0 100 = 10 Diameter Series 221 = 220

T: 800-808-2434 : 775-884-2434 (Outside the United States and Canada) : www.ametherm.com : [email protected] T: 800-808-2434 : 775-884-2434 (Outside the United States and Canada) : www.ametherm.com : [email protected] T: 800-808-2434 : 775-884-2434 (Outside the United States and Canada) : www.ametherm.com : [email protected]

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