Over voltage protection circuit using mosfet

Question

I need over voltage cut off circuit.

If input voltage goes above 440V input power should cut off , once input voltage is back to normal 230V then switch (MOSFET) should be conducting and when supply voltage is greater than 440V MOSFET should not conduct**). ? plz help

What is behind the circuit ? More specifically: do you have a diode bridge as the first stage and can the protection circuit be placed after this diode bridge, so it handles only high-voltage DC ? Or does the protection circuit have to accept AC voltage ? — dim, Apr 26 '16 at 10:22
Why don't you design your power supply to be able to work at 230V and 440V AC? A simple way is use a standard SMPS with a 2:1 transformer on the power input hence 230V becomes 115V and 440V becomes 220V. — Andy aka, Apr 26 '16 at 10:36
@Andy well, that would become more expensive than an appropriate protection circuit. — dim, Apr 26 '16 at 11:00
@dim please allow the OP to answer that - if I wanted someone else to answer that I would have made it perfectly clear. Adding a transformer adds cost - that DOES NOT need to be said because it is clearly obvious. — Andy aka, Apr 26 '16 at 11:04
Andy, on this forum cost is a forbidden word. A question related to cost is banned. So it actually cannot be said and not being punished. — , Apr 26 '16 at 11:09
??? I think the implications of what I said are now beyond me. Sorry if I offended anyone. — dim, Apr 26 '16 at 11:15
Putting transformer is not a solution to my problem but thanks for the suggestion — Nikhil Joshi, May 01 '16 at 10:48
@dim ..... yes protection circuit is after the bridge rectifier. — Nikhil Joshi, May 02 '16 at 13:17
@dim.. yes i want to put the circuit after the diode bridge.. so only for dc — Nikhil Joshi, Jun 28 '17 at 09:30

dim · Accepted Answer · 2016-05-02T13:26:43.690

Honestly, I don't know if this circuit is appropriate for your specific needs as you didn't give much details, but just for fun, here is what I came up with. It must be located between the supposed diode bridge and the rest of the circuit to protect (it takes DC current as input).

Explanations

The D1+R1 part forms a small 10V supply (you may need an additional capacitor across D1). R2+R3 is a voltage divider. When the voltage divider output goes above 10V (which happens when the supply goes above ~400V), Q1 starts conducting, which in turn makes Q2 conduct and shuts down the mosfet. When the fault disappears, everything goes back to normal, but it takes a longer time.

There may be ways to make the circuit simpler. For example, you can eliminate Q2 by exchanging Q1 base and emitter, but in this case, it takes longer to shut down from the fault than to recover.

Component choice

You have to be careful on the choice of the mosfet. It has to withstand the maximum fault voltage you want to prevent. Also, R1 dissipation must be rated appropriately: 1W is the minimum, may be more, depending on the voltage you want to handle. Also use appropriate diodes for the bridge, they also should withstand the max fault voltage.

Operating conditions

Power consumption of this circuit under normal conditions is about 0.3 Watts.

Shutting down due to an overvoltage takes about 100µS. Recovering when the fault disappears takes about 400µS.

Edit

This is the source of the circuit, for reference

Version 4
SHEET 1 1012 700
WIRE 240 16 64 16
WIRE 384 16 240 16
WIRE 912 16 384 16
WIRE 240 64 240 16
WIRE 384 64 384 16
WIRE 64 144 64 16
WIRE 240 208 240 144
WIRE 320 208 240 208
WIRE 496 208 320 208
WIRE 592 208 496 208
WIRE 768 208 672 208
WIRE 912 208 912 16
WIRE 64 288 64 224
WIRE 240 336 240 208
WIRE 496 336 496 208
WIRE 768 352 768 208
WIRE 768 352 656 352
WIRE 384 400 384 144
WIRE 448 400 384 400
WIRE 592 400 544 400
WIRE 384 432 384 400
WIRE 768 480 768 352
WIRE 240 528 240 400
WIRE 240 528 64 528
WIRE 384 528 384 512
WIRE 384 528 240 528
WIRE 656 528 656 448
WIRE 656 528 384 528
WIRE 752 528 656 528
WIRE 912 528 912 288
WIRE 912 528 848 528
WIRE 64 576 64 528
FLAG 64 288 0
FLAG 64 576 0
FLAG 320 208 10V
SYMBOL voltage 64 128 R0
WINDOW 3 -489 44 Left 2
WINDOW 123 0 0 Left 2
WINDOW 39 -488 73 Left 2
SYMATTR InstName V1
SYMATTR Value PULSE(200 600 10m 10m 10m 10m 40m)
SYMATTR SpiceLine Rser=.1
SYMBOL nmos 848 480 R90
WINDOW 0 118 71 VRight 2
WINDOW 3 88 -22 VRight 2
SYMATTR InstName M1
SYMATTR Value STW11NM80
SYMBOL res 896 192 R0
SYMATTR InstName Rload
SYMATTR Value 1k
SYMBOL zener 256 400 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D1
SYMATTR Value BZX84C10L
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res 224 48 R0
WINDOW 39 36 104 Left 2
SYMATTR InstName R1
SYMATTR Value 470k
SYMATTR SpiceLine pwr=1
SYMBOL res 368 48 R0
SYMATTR InstName R2
SYMATTR Value 2.2Meg
SYMBOL res 368 416 R0
SYMATTR InstName R3
SYMATTR Value 57k
SYMBOL pnp 544 336 R90
WINDOW 0 66 65 VLeft 2
WINDOW 3 93 63 VLeft 2
SYMATTR InstName Q1
SYMATTR Value BC857B
SYMBOL res 688 192 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R5
SYMATTR Value 57k
SYMBOL npn 592 352 R0
SYMATTR InstName Q2
SYMATTR Value BC847B
TEXT -426 382 Left 2 !.tran 100m

i tried to simulate it but mosfet is not conducting.. but m still trying to simulate the same circuit.. — Nikhil Joshi, May 02 '16 at 13:10
Well, I simulated it myself and it worked. If you are simulating it as part of a bigger circuit, you might have to change a few parameters. — dim, May 02 '16 at 13:23
@Nikhil I added the LTSpice circuit description, so it's easier to check. — dim, May 02 '16 at 13:28
Hey thnx I will try this and discuss wid u tomorrow thnx a lot — Nikhil Joshi, May 02 '16 at 13:51
can u mail me that file on this address plz nikhiljsh17@gmail.com that will be a great help — Nikhil Joshi, May 03 '16 at 07:29
I'm sorry, I don't wanna give my mail. Just copy the source of the circuit that I have added in the answer, paste it in a text file, rename the file "whatever.asc", open it in LTSpice. It shouldn't be too hard. — dim, May 03 '16 at 07:51
M using multisim I did the same renamed it nik.cir but it shows some wiring n is giving errors — Nikhil Joshi, May 03 '16 at 08:10
Well, because it is a LTspice shematic. Download LTspice, it is free. I never used multisim, but I doubt files from LTspice can be used with multisim as is. — dim, May 03 '16 at 08:26
Thanks dim this is exacctly what I was asking for.. thanks a lot..It's working .. — Nikhil Joshi, Jun 28 '17 at 09:37
@nikhil Wow, one year later... It did take a long time to get these components delivered, it seems. — dim, Jun 28 '17 at 09:40

score 0 · Answer 2 · answered Apr 26 '16 at 11:02

0

How about a comparator driving a relay, when the measured voltage exceeds a preset value, the relay is turned off, when the voltage comes back into range it's turned on again, you'd need a small supply for the comparator and relay though

answered Apr 26 '16 at 11:02

Sam

3,709
13
16

can we use mosfet as a switch , i want it compact so i dont want to use relay. Thnx. – Nikhil Joshi Jun 14 '17 at 07:03
@NikhilJoshi There's no reason why you can't replace a relay with a MOSFET, just be aware that with an N channel FET the gate needs to be raised 5-10V above the voltage on the source terminal to turn it on while a P channel FET need a gate voltage 5-10V below the source voltage to turn it on. This can sometimes make the drive circuitry more complex and you lose the isolation and bidirectional current switching that a relay provides. – Sam Jun 15 '17 at 07:48

Over voltage protection circuit using mosfet

2 Answers2