Questions tagged [inrush-current]

The high current, that often occurs when first plugging an appliance in the power supply.

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Model positive exponential current curve on LTSPICE

I am trying to model the inrush current for a contactor. From the specifications I should get something like this: The hold current is 0.13A and the inrush current is 3.2A. This is controlled using R3 ...
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Dealing with inrush current - input resistor?

I've got a circuit that's having problems at startup with inrush current, leading to large spikes on VCC (parasitic inductive of the power supply / leads etc) that sometimes results in smoke coming ...
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Inductor calcualtions to limit inrush and avoid oscillations in power line

I want to design a circuit that is able to supply my load with 12V at 2.3A for around 10ms when the power is switched off. The capacitor size will therefore be 23000 uF, assuming a 1V sag. Applying ...
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Relay does not turn on when using a 2.5A 12V power supply

I have a relay that I am using for a project. The relay datasheet is here. I am using a 12V DC 2.5A power supply to supply power to the relay above, datasheet. From the datasheet, however, I saw that ...
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Bigger NTC = better protection?

A 2.5 ohm NTC is used in the following PFC booster. I've got a 20 ohm one. Can I use it instead of 2.5ohm one? Does it provide better protection or does it disturb the normal operation of the circuit?
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Is Stall Current Generally Equal to Inrush Current?

I haven't been able to find a clear or definitive answer on this, and I've been wondering about it for some time, now: Does the peak inrush current of an electric motor equal the peak stall current of ...
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Are inrush thermistors thermally insulated?

Vaguely related to this question but with some different questions and a different component. For an inrush-limiting NTC thermistor such as the Ametherm SL series: It seems purposefully designed to ...
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VFD filament inrush current resistor

How can I calculate the resistance for a minimization inrush current effects, to increase the life of the filament of a VFD tube (IV22). Or is there another technical solution to prevent the filament ...
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Break peak inrush current

I want to renew a 30 Year old line-filter 230V AC for an electronic device. At the end of the filter is a 230V transformer with 9 secondary outlets: 5.8V, 51.4V, 16V, 13.3V, 9V, 9.8V, 18V, 80V, 100V. ...
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Why is my battery showing a huge negative inrush current in my designed charger model?

I have a three-phase charger model on simulink as shown below, with a three-phase active front end converter followed by a phase-shifted full bridge DC/DC converter. The circuit is working pretty ...
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133 views

Inrush current handling for relays

I am building a controller (ESP based) to sit in front of a Meanwell LED Driver (HLG-150H-12B). I intend on using a trigger relay module to switch the 230VAC-Live into the HLG, however I am slightly ...
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Load current high-side power switch

I have some motors connected to a battery which I start with a switch. I suppose they have some big capacitors inside their drivers so when I turn on the motors with the switch, they draw a big ...
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Would this inrush current circuit work in practice?

I am building a USB hub circuit, which, because of the 120uF capacitance requirements on upstream USB ports, means that I need to charge those large capacitors in my circuit. However, my hub will be ...
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4 answers
437 views

Limit inrush current for USB and large capacitors

I am building an ESP32 custom board (project link and full schematics/layout.) I want to add USB to it for programming only. Power Supply: USB to serial: During normal operation, the board will be ...
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Limit inrush current to capacitor bank

My goal is to drive a beefy solenoid (1.6 Ohm / 1.5 mH / 50ms actuation time, once every 1-2 seconds) from a 36mF (3x12mF in parallel) capacitor bank at 24V, charged from an 1A PSU. This capacitor/low ...
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Choice of AC/DC power supply for PTC heater with inrush current

I want to power 2x PTC heaters mounted in parallel with a 24VDC power supply (this one). If possible I would like to avoid using a current-limiting system to handle the inrush currents. The specs of ...
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Motor Controller doesn't precharge

I want to include a precharge resistor in parallel with my contactor to charge up the capacitors on my motor controller. This way, there won't be a large in-rush current through the contactor when I ...
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Ramping up Regulator Voltage on Switch On

I'm currently trying to design a supply using a low dropout regulator capable of 1.5 A that has a high capacitance of up to 1 mF at its output. To limit inrush current I would like to ramp up the ...
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Use SCR and resistor as an inrush current limiter

I try to design an inrush current limiter using an SCR S2800F (https://datasheetspdf.com/pdf-file/1129612/Motorola/S2800F/1) and a resistor, as shown in the below diagram. A 600 VDC power supply ...
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Estimating load capacitance from inrush current

I need to estimate the capacitance of a load for choosing a PSU for it, as they state the maximum capacitance. It is a strobe light so I suspect it will have quite a bit of capacitance. I've tried ...
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How to spec a inrush current resistor?

I want to know how do I spec a limiting resistor for the below circuit: The relay used is this. The power supply input is 48V and the output is 12V DC. First switch SW1 is pressed which powers the DC/...
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Control PMOS or NMOS for Soft Start with Variable Voltage Source (Battery or known series string of solar)?

I have a soft start circuit that looks like so: The load will actually be a synchronous boost/buck converter, and ultimately this could also have an AC source instead of just DC and have a rectifier ...
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Why AC motor driver shorts out?

I have been working in a VFD using an AC motor driver FSBB30CH60DF and making control of it using a dspic30f4011. As you can see in the attached circuit schematic, the mains supply is a single phase ...
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Clamping inrush current in a lighting circuit

I use a relay to switch on/off lighting circuits with lots of LEDs. The relay switches the mains supply so must run happily with 110/220/240 Vac. The relay I'm using is rated for an 800 A inrush ...
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For calculating inrush current in a ceramic capacitor , do we need to consider the effective capacitance after derating for dc-bias effect?

Inrush current happens when capacitor is initially charged from 0V to the intended rail voltage. What should be the effective capacitance to be considered during this charging? -Since the voltage ...
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Switch-on time of an active p-channel MOSFET current limiting circuit

I have recently posted a question on the design of an inrush-current limiting circuit: Current limiting circuit with P-Channel MOSFET I have decided to post a new question on how to analytically ...
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3 votes
2 answers
429 views

Current limiting circuit with P-Channel MOSFET

I am designing a simple inrush current limiting circuit with a P-Channel MOSFET: The simulation shows a 48V source that switching on with a fairly fast rise time of 1ns. The Drain-Gate capacitor ...
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1 vote
3 answers
82 views

Inrush control transient at power on

I have a circuit with a not-so-small capacitor on the supply and I need to reduce the inrush surge; as a matter of fact the power supply breaks after a while (these cinese supplies are not fun) I ...
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1 answer
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Is the dipping in VCC caused by inrush current of charging 1 uF and 0.1 uF capacitors?

I'm powering MSP430FR5994 microcontroller from a power supply using a 2.2 V regulator. This regulator can source up to 200 mA. When MSP430 turns on, it starts to charge a 1 uF and 0.1 uF by driving ...
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What are the implied peak current ratings of GFCI's?

Using GFCIs with transformer or other high-inrush current loads is problematic, because in some designs the differential transformer core can locally saturate and produce an invalid output in the ...
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Active inrush current limiter using relay

I'm concerned about the delay of a typical relay used in this circuit: DC: voltage from a low quality switching regulator. R : high wattage current limiting resistor. Cap : group of parallel ...
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2 answers
217 views

Improving this circuit from Texas Instruments note (inrush current)

this is an example circuit in this PDF from TI. (page 19, inrush current stuff) Description : In steady-state operation, Q1 is fully turned on and load current flows through the series sense ...
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1 vote
1 answer
82 views

Would sparks from connecting power adapter to DC jack cause issues to a circuit?

When connecting a power adapter (19V) to a circuit through a wall mount DC jack, I get these sparks. Would this cause any damage to the circuit, and if so what would be the solution other than not ...
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2 votes
4 answers
268 views

Limiting the Inrush current of the Boost converter device?

I have a source of 24 V and I cannot draw more than 2.4 W from the same. This means I cannot draw a current more than 100 mA from this supply. Alongside the LM5001 boost converter, it also has some ...
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High-side mosfet switch placement

this is a power circuit I'm trying to complete: the button at top turns the curcuit on, supplying VCC to mcu, and the MCU will output a high signal to a pin (marked in pink) which turns the N-MOSFET ...
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Super Basic Inrush limiting for super capacitors

I have 6 x 500 farad super caps in series. I want to use them to smooth voltage dips in a 12v system that is powered by a DC-DC converter. Currently my application is a water pump (desalination) ...
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320 views

How to limit Inrush current from a DC motor?

I'm new to this platform and knows very little about electronics. Please forgive if any of this is dumb. I wish to create an inrush current protection for my L298N Motor Driver, which drives a 7.5V DC ...
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1 vote
2 answers
244 views

Using supercapacitors on DC-DC converter output for high in-rush current

I have a motor that draws a max continuous current of 60A, but has a peak in-rush draw over 120A for a few milliseconds. I want to power the motor using a DC-DC converter. I purchased a converter that ...
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Solid State Relay for Large Inductive Load

I have an old, transformer-based welding machine, which is rated to draw about 70A at 240V, at full output. It uses an electro-mechanical relay (contactor) to energize the main power transformer, and ...
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4 votes
1 answer
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Why do European motorized appliances draw less inrush current than their American counterparts?

I have been trying to tease apart the history and evolution of arc fault circuit interrupter requirements, and in the process, came across a curious historical sidenote early in its genesis, namely ...
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Why would a multimeter (ammeter) connected in series prevent the instrumented device from powering on?

I'm trying to measure the current used by a 3.5" hard drive in an external enclosure. I connected my multimeter in series with the positive 12V power supply, but in doing so, the hard drive ...
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1 vote
0 answers
87 views

Limit inrush current after emergency stop relay

I have a power board with an emergency stop (using a mechanical relay). The input voltage is 24V and on the power board I have multiple DCDC converters, some before the emergency stop and some after. ...
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Duration of inrush current for high pressure sodium lamp with electronic balast

I'm trying to find reliable information regarding the duration of inrush current for high pressure sodium lamps with electronic ballasts. This document states that: "In reality, due to the ...
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Hot-plugging power kills switch-mode converter

We have a small IoT device, that runs of an external 24v DC power supply brick (https://www.rapidonline.com/tt-electronics-t6367st-24vdc-60w-installation-smpsu-85-3795) This 24v supply connects to the ...
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Smart load switch with inrush control and overvoltage lockout

After I finish making my dc-dc buck-bost converter, voltmeter and ammeter I decided to add a smart load switch to my power supply in order to have the posibility to connect electric motors, bulbs or ...
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The right fuse (inrush current problem )?

Hello Electrical Engineers, just a quick question I need to get a fuse between the mains voltage (120V) and the adapter. I know that the load will draw around 30mA and has an operating voltage of 24V. ...
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160 views

Transistor current limit

Suppose the DC motor has a peak current of 500ma and after that it drops to 100ma, the transistor can switch continuously 200ma. If I limit the current of the transistor from the base current to 100ma,...
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1 answer
181 views

Inrush current in the Boost Converter during start

I am making a 400V 1kW boost converter but in the LT-SPICE simulation, it is drawing a huge current of 50-60A at the start for 1ms-3ms, but the current comes down to 12A after that. The inductor ...
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ESP32 stalls b/c of current spike (inrush current) - how to limit inrush current?

I have a circuit with several neopixels and an ESP32 MCU running with micropyhton. Under full load, the circuit including the ESP32 draws around 200mA at full load. Now I'd like to add another ...
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1 vote
2 answers
135 views

High current problem

I have this circuit: I was asked to measure the inrush current for this circuit section. One floating output actually goes to a microcontroller input and the other goes to an op-amp input terminal. ...
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