and cant figure out why the motor is 1.5 hp 1160 rpm 480 motor with three 6 1/4 amp fuses and i megged all wires and everything is good anyone have any ideas??? We use cookies to give you the best possible … The squirrel cage brand is the most popular and they perform various tasks wherever they are applied. Swapped it for another. 3 … A short between the two multiplies the current flowing BACK through the fuse of L1. So there is a piece of equipment that routinely blows fuses. There are 8 lights within that 150 metres on the red and blue phase.the cables appear to loop in and out of the columns but may be jointed under ground, any thing is possible.and in the column is a mini is a double pole isolator and fuse carrier. Three phase fuse failure relay is intended for continuous monitoring of potential transformer fuses. The size installed are FRS-R-20. i have a 3 phase 480v fan motor that keeps blowing fuses. JavaScript is disabled. Interested in this topic? It’s a 3 phase supply each with a 63A fuse. The transformer produces 30v 1000va from 230v mains \$\endgroup\$ – Michael Tuttle Sep 15 '13 at 11:44 | show 1 more comment By joining CR4 you can "subscribe" to The top is line voltage from the busbar. The cause is, for example, blown fuse. Thousands of customer product reviews. The motor then continues running with two phases and can suffer damage. Fuse characteristics can be classified into three general categories: very fast-acting, fast-acting, or Slo-Blo® Fuse. The fuses are LPJ-30SP , it was fully functional before the mechanics pulled it. Scenariao:Three phase (3 x 100A) supply entering church building. The issue, I assume line one (farthest left bank in the breaker) is consistently blowing the fuse after the compressor runs for half a day or so. Choose from top trade brands. It has been blowing a single fuse, single phasing then dropping out on overloads. Which is precisely why he should seek professional help. - Answered by a verified Electrician. Each time the breaker is tripped or fuses blown. A phase failure is an interruption of a single conductor. I have a 208V 3 phase wye system and every time I try to connect the motor to it blows fuses on two out of the 3 legs. A time-delay fuse (also known as an anti-surge or slow-blow fuse) is designed to allow a current which is above the rated value of the fuse to flow for a short period of time without the fuse blowing. Also if the fuses are not slow-blow, and are not rated to handle the initial LRA or locked rotor amps from the motor starting from a stall or stop, the fuses will pop. When a three phase motor looses one of the phase supply voltage then it is called Single Phasing.Single Phasing a case when any one phase out of the three phases fails. Testing a 3-phase motor is as simple as holding the leads of a volt ohmmeter. DIY and save $300-$500. Check for ground faults: Disconnect the motor’s power source. It's been three days since the poster has said anything at all, and that was the post that started this thread. Why does that happen? The old motor that was installed was set up for 440V, running this with a 220V I think it is just that the fuses are to small. The second time it blew the C phase fuse. 3 phase appliance blowing fuse. We should probably try to tone the conjecture down until the original poster comes back and responds to what's already been said. Hey...we like to breath down on each others neck. The leg "B" is going to L3. But if we add to the circuit lots of resistance, the fuse also burns, because these elements consume much more power and current is getting bigger. However, if the motor was running and one of the fuse blows off, the motor will continue running drawing high current, ultimately burning out. This is called single phasing of 3phase induction motor. Same fuse, same spot everytime. Discussion in 'Electricians' Talk' started by Unicorn, Aug 22, 2018. You must log in or register to reply here. What is everyone talking about anyways? Interestingly if you observe the instantaneous power waveform it too varies in relation to the sinusoidal voltage and current. Small to medium sized motors are mostly stator critical – this means that only the stator can be damaged. When you say that you have "a 208V 3 phase wye system" do you mean that the 208 volts is between neutral (Star point.) A three phase heater has fuses on each phase, one of the fuses blows, what is the output of the heater? Each time the breaker is tripped or fuses blown. Normal fast-blow fuses are the most general purpose fuses. If the supply (rms) voltage and load impedance values are stable then the. Phase failure. The trick is knowing which leads to hold on to and which wires make no difference at all. It has been blowing a single fuse, single phasing then dropping out on overloads. Unicorn Member. When a three phase motor looses one of the phase supply voltage then it is called Single Phasing.Single Phasing a case when any one phase out of the three phases fails. Get a qualified electrician to take a look at it. Or, it may indicate that your house has too few circuits and is in need of a … But why? This 10 amp fuse controls shifting out of park, the tu … read more The fuses are Cooper Bussman 20A time delay fuses. Three phase motors will not start on single phase current. - Answered by a verified Electrician. "Why does my Motor keep blowing Fuses and Tripping Breakers? Lowes item #: 286530. I went to troubleshoot a motor that is blowing fuses on one leg of a 3 phase motor, its fed from a 1 phase to 3 phase converter(no nameplate on the converter) the line side breaker is 100A, Im assuming its a 3 phase … This transformer is used to power the brake control module I replaced the one of 3 fuses and it started up fine but then a different fuse blew upon braking. What will happen if one of the fuses blows off in a three-phase unbalance load? They are used in situations where large power is required. The transformer produces 30v 1000va from 230v mains \$\endgroup\$ – Michael Tuttle Sep 15 '13 at 11:44 | show 1 more comment Sorry it is a 3 phase and I have a Phase-o-Matic, PAM-1200 HD driving it before the fuses. and each pase or do you mean that there is 208 volts between phases ? On a three-phase delta-why connected transformer when one of the primary fuses blows up (on the high tension side) the effect on the secondary side will be: 1- one phase will be lost. I believe this is happening because a 10 amp fuse keeps blowing. Sorry it is a 3 phase and I have a Phase-o-Matic, PAM-1200 HD driving it before the fuses. Wire Size and Fuse Ratings for 3-Phase Induction Motors; Womack Data Sheet 78: Wire Size and Fuse Ratings for 3-Phase Induction Motors. If the main fuse is blown, DO NOT apply power to the motor until you have replaced defective fuses and checked for any ground … Basically one of the three main fuses has blown twice now so I’m told. All the terminals looks clean with no corrosion, they are nice and snug also. 60 days free credit available. This is a rough diagram of how it is setup. For 240-volt circuits that control major appliance circuits, such as an air conditioner or electric range, the fuses are small cartridge devices that fit between metal contacts, usually fitted into a fuse block that can be pulled out from the fuse panel in order to change the fuses. 30 day money back guarantee. AC basically means constantly changing voltages. I connect the green from the motor to the ground terminals in the panel where the 120v is tapped into. FUSE CHARACTERISTICS: This characteristic of a fuse design refers to how rapidly it responds to various current overloads. It is sized for a 10HP motor. typically derated 25% for operation at 25°C to avoid nuisance blowing. A three phase heater has fuses on each phase, one of the fuses blows, what is the output of the heater? Dead shorts of course the fuse blows, but if you add resistance it has to be enough to limit the current to the point where the fuse won't blow. Buy 3 Phase Distribution at Screwfix.com. For ... pertain to the melting phase portion of the “clearing” or “opening”. If we make a dead short, then the fuse burns out. It just had bad bearings. Power is ran through a 240v 3 phase 60 amp breaker, currently the breaker is running 50 amp fuses. My stepper motor isn't working properly( its taking less steps then it should)(Arduino), Properly powering 20T Brushed Motor and measuring Amps. Three phase induction motors are one of the most popular electric motors commonly found in processing plants or any manufacturing concern. Going to start looking for problem Monday but did have time to do some voltage checks before closing for weekend. According to Ohm`s law if resistance is getting bigger, then current must get smaller. Switch opening is initiated by the fuses near the transition point of a 3-phase fault. Or more likely, they have successfully barbecued themselves across the 3 phase supply!! My question is why do I get a reading of 480V phase to phase on the line side of the fuses and with one fuse removed am getting a reading of 235V on the load side of the fuse holders with the one phase fuse … The 3 phase motor will not start and the the motor will burnt out due to flow of high locked rotor (short circuit) current. The old motor that was installed was set up for 440V, running this with a 220V I think it is just that the fuses are to small. The original question make no sense, no multiphase system has a voltage which does not change. 3- the other one will stay almost the same. After the normal checks I determined a fuse supplying power to a transformer in the unit was blown. The fuse is housed in one of those old 3 phase isolator switches with the big handles, it then from there supplies a 3 phase heating contactor then from there one of the three consumer units. No. Since one of the phases is now disconnected, current through other … Since one of the … You're still applying a low enough resistance that the fuse is blowing from what little information you've provided. For example, a fuse with a current rating of 10A is not usually recom-mended for operation at more than 7.5A in a 25°C ambient. I can understand that, because current is getting bigger and there is relatively small resistance. 2- another phase will dim. The monitoring relay is used for continuous monitoring of fuses against blowing out or inadvertent removals and may cause incorrect tripping. blown fuse on three phase transformer The second time it blew the C phase fuse. When a circuit breaker regularly trips or a fuse repeatedly blows, it is a sign that you are making excessive demands on the circuit and need to move some appliances and devices to other circuits. Pathfinder Tags: electrical. The first time it did this it blew the B phase fuse. Is FRS-R-20 a 20 AMP fuse? The leg "B" is going to L3. Problem: yesterday a fuse on the primary isolator blew. You need to give more details because this doesn't make sense to me either. After replacing that fuse it started and stopped fine multiple times after. With individual fuses on each phase, it is just three, single phases (120deg from each other in order), so when L1s sinusoid is swinging negative, L2 is still in the positive. The OP was blowing fuses, you can't get much more practical than that!!! The size installed are FRS-R-20. These provide a very short delay to prevent blowing a fuse during the short interval while the motor is accelerating up … These feed a primary isolator containing 3 x BS88 60A fuses. Earlier this year I installed a phase inverter in a woodworking shop to supply several 3 phase … I keep blowing the fuses, and I cannot figure out why. Agreed. You must log in or register to reply here. I don't think it anything to do with grounding. The fastest fuse blows, thereby interrupting one of the phases, and its striker commands the opening of the switch. The power waveform frequency is twice the source frequency. star or delta connection or what ever ..does not matter. It is sized for a 10HP motor. The first time it did this it blew the B phase fuse. This is different from a single phase compressor which will have 3 terminals listed as S, R, and C (Start, Run and Common). It always blows Fuse A. Register to Reply. Blows the 3 amp fuse on the control board for my Goodman AC unit. 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