Here we can also use 24v operated items, but for 24v supply, also require 24v SMPS. If our all contactor and timer is operated on 220v-50hz, then control supply require 220v single phase.
Star delta problem pdf full#
After some time or motor achieve full speed, motor winding connection convert in to delta connection automatically. In this starter, when motor started, motor runs in star connection, it means first of all, main contactor and star connector on. Figure 4: power circuit diagram of star delta starterįigure4- power circuit diagram of star delta starterĬontrol circuit diagram:- Before making circuit diagram we know how its work or working principle. Now power connection is ready.Īfter merging all step showing in figure 4.
Like U1 connect to W2, U2 connect to V1, V2 connect to W1. There we use our mind how we connect U2, V2 and W2 in delta contactor because we want to make delta winding when this contactor on. Step4:-Now we connect R1, Y1 and B1 with delta contactor (C2). Using this short wire we make star winding showing in figure 2. And all input of star contactor short with wire.
Step3:-Now we connect U2, V2, and W2 in star contactor output (C3). It means R, Y and B phase connect to U1, V1 and W1 through MCB, overload relay and main contactor. Step2:-overload relay output connect to Main contactor input (C1) and main contactor output (C1) connect motor three wires as U1, V1 and W1. Step1:- line voltage(R,Y,B,) connect in MCB input and then MCB output connect to overload relay input.įIGURE1:- STEP 1 AND 2 or initial connection Lets start to make power connection diagram Figure 1: Here overload relay is use for protection from heavy current. To make power connection diagram we require 3 contactor, 1 overload relay and 1 MCB. Power connection diagram:-Ħ wire of winding is coming from motor as U1, U2, V1, V2, W1, W2. That’s why torque is reduced by factor of three.On the other hand in delta connection winding voltage is equal to line voltage and winding current is equal to 1/√3 line current. We know that in star connection winding voltage is equal to 1/√3 of line voltage but winding current is equal to line current. In this starter motor is running in star winding during start, when motor get full rpm, winding convert in to delta winding. Star delta starter used to reduced starting voltage.This also reduces the torque. Two methods are used for reduction of starting voltage are star delta starting and auto transformer starting To limit the starting current flow, large induction motors are started at reduced voltage and when motor achieve own rotation speed, full supply voltage reconnected. Due to large current, they cause disturbance in supply voltage. Most induction motors are started using direct online starter, but when very large power motors are started using DOL, they take large starting current. It’scost effective and simple operationas compare other voltage reduced starter. Star delta starter is most commonly used starter after direct online starter in electrical world.
Star delta starter:- reducing voltage at starting time.Direct online starter:- apply direct voltage to motor.There are following types of starting method of motor. Motor is taking current higher than rated current without trip.Improper ventilation or high ambient temperature.If Rotor is not smooth change bearing of motor.
Star delta problem pdf free#
Check rotor by hand or manually, rotor should be free or no abnormality.Disconnect Motor from load, and check current.Check mechanical load on motor, Load should be smooth or not in jam condition.If resistance of winding is unbalanced, motor is faulty. Voltage should be in specification range. Q2- Why motor is drawing current more than rated current?Īns- Motor is drawing more than rated current due to following reason:. If we found resistance unbalanced or not same. If we found continuity between earth and winding, motor is faulty.If we found infinity resistance or no continuity in any winding, motor is faulty.
Star delta problem pdf series#
But by series tester we can check only continuity not accurate resistance. Here we use multi-meter or series tester to check. Q1- How we check motor is in working condition or not?Īns- Open all connection of motor.
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