LV Motor Over Load

You have not stated what type of load you are driving with the motor, but like any physically realizable device it has limits, and you have exceeded them.

Rotary feeders, screw conveyors.

I am I having one scraper chain, which so long form load centre, aprox 1km and i getting voltage 400 to 410V, and while starting this chain conveyor it is taking very high load, voltage drop to 300V, to start this chain we have to increase the voltage form 440V.

This increase in voltage, trips the rotary feeders, screw conveyors at load centres MCC

This is nothing more than the electrical equivalent of Fudd's First Law.

A web address just for that...now that's a good use of the internet.

You overloaded it.

Dude, that's the design limits.

Wow, you're definitely fired, once your superiors find out what you're doing.

Try, something else.

Well now at least you know. Stay sober alright?

You have the answer...it is trip by overload because that is the design limit!

lim·itˈlimit/nounnoun: limit; plural noun: limits

1. 1. a point or level beyond which something does not or may not extend or pass."the limits of presidential power"
• the terminal point or boundary of an area or movement."the city limits"

  synonyms:

  boundary, border, bound, frontier, edge, demarcation line; Moreperimeter, outside, confine, periphery, margin, rim "the city limits"

• the furthest extent of one's physical or mental endurance."Mary Ann tried everyone's patience to the limit"

  synonyms:

  utmost, breaking point, greatest extent More"resources are stretched to the limit"one's/the breaking point, the last straw; informalthe end, it, one's wits' end, one's/the max "I've reached my limit !"

2. 2. a restriction on the size or amount of something permissible or possible."an age limit"

   synonyms:

   maximum, ceiling, limitation, upper limit; Morerestriction, check, control, restraint "a limit of 4,500 people"

• a speed limit."a 30 mph limit"
• (in card games) an agreed maximum stake or bet.
• the maximum concentration of alcohol in the blood that the law allows in the driver of a motor vehicle.noun: legal limit; plural noun: legal limits"the risk of drinkers inadvertently going over the limit"
3. 3. Mathematicsa point or value that a sequence, function, or sum of a series can be made to approach progressively, until it is as close to the point or value as desired.

verbverb: limit; 3rd person present: limits; past tense: limited; past participle: limited; gerund or present participle: limiting1. set or serve as a limit to."try to limit the amount you drink"

What worries me more is that management wants the OP to "fix" this.

"To hell with the equipment protection, get it running."

Unless you're taking enemy fire, run away from any boss that tells you this.

I guess, he's running a destructive testing Redfred, must be from R&D department.

According to IEC 60076-1 ch.7.3 Voltage and frequency variations during operation Figure 12 - Voltage and frequency limits for motors

if the frequency stays as rated then up to 5% increased voltage will not change the all other rated properties [current, torque, slip].Up 10% overvoltage it will be still permissible. After then the no-load current will rise very much [due magnetic core saturation].Also the winding insulation may be damaged if the overvoltage is very high.

However, you may increase the voltage increasing the frequency in the same time keeping the magnetic flux constant. Of course, the limit it is the insulation permissible voltage.

Sorry,I meant IEC 60034-1[IEC 60076-1 it is for power transformer standard!]

Try VFD

Because by doing that there is a risk of turning it from a motor to a convector heater, and it isn't designed to be a convector heater. So the overload device has prevented it from happening by disconnecting the power.

I think it has become a habit to beat around the bush in CR4. Calculate current value for the load ( which could be calculated based on normal voltage and current at that period. Then check the FLA rating of motor and also the setting of Over Load relay. You will come to to know the reason. Mostly at higher voltage current increases as motor parameters are mostly fixed. Set the OL relay to proper level within FLA.Beyond FLA motor windings may get damaged. This phenomenon may be commonly found on systems with substantial initial load.

I think it has become a habit to beat around the bush in CR4.

you noticed!!

Actually is called.. extracting the urine!!

While the whole purpose of the forum is to exchange experience and ideas, help those that are stuck and so on, it becomes open season when a post such as we have receivd from the OP, is either a wind up (can anyone be that stupid really?) or they should NEVER have left their job in McDonalds.

It is quite apparent by some of the questions posed that in many cases the OP knows the square of nothing in the subject matter related to the question, and is looking for someone to do his work and get him out of the merky mire!

Stick around.. it's gets better!! and if you think this is bad... wait until a 1st year electrical student asks us to do his homework...

Please look at the bottom line of my postings.

I have once strongly messaged about it.

Why cant we be strict enough - not to respond such queries or respond straight on face to refer text books or net search rather than beating around the bush ... I feeel facing head on shall be a better way.. you all may discuss if need be or let's start.

OK, aside from the regulatory issues and such, the CONCEPT behind it all is this;

An induction motor does the work of providing torque at a given speed, the result is called kW or HP, depending on where you are. In the course of fulfilling that basic function, there are deeper design elements that are involving the magnetics that take place inside of the motor stator and rotor, the stuff that turns the steel and copper into something other than a boat anchor.

In those magnetic details, a PORTION of the current that flows to the stator is creating the magnetic FLUX inside of the motor, the remainder is creating the TORQUE in the motor. The RATING of the motor is the optimum confluence of those issues without creating more heat in the motor than it can handle safely. If you increase the voltage, it begins to increase the FLUX producing current much faster than it increases the torque. So you begin to get less bang for your buck as we say here in the US, meaning less gain in performance than loss of efficiency. That translates to the fact that the added flux producing current is increasing the heat by virtue of more current flowing, but without a corresponding increase in output mechanical power, or at least not at anywhere near the same rate.

The feeder conductors are too small,causing excessive voltage drop at the scraper motor.

Increase the feeder conductor size to solve the problem.

Information needed will be:

FLA of motor,Locked Rotor Amps of Motor,Service Factor of Motor,Power Factor of Motor.

The designed voltage and frequency of the motor,and number of phases.

The available voltages at the Main Control Panel,1 Km away,and the available amps from the Main Control Panel.

The highest ambient temperature that the conductors will encounter,and how the conductors are routed,: Direct Buried underground,underground in conduit,or aerial span.

Provide ALL of this information, and I may be able to help you determine the best remedy.

The problem can not be effectively solved without all of this information.

As I understand, before the voltage was raised to 440 V it was a problem at start. In my opinion

the conveyor was overloaded or even locked and or the motor torque was wick to overcome the load. The starting torque is proportional with square of supplied [at motor terminals] voltage.

It seems to me at 440 V the start [ 325 V at the motor terminals- may be] was successful but after then at steady state the motor was still overloaded-this not due to overvoltage but the conveyor overload. In my opinion if you cannot discharge the conveyor you have to change the motor.

Because, during the high voltage , motor to draw excessive current to magentize the iron beyond the point where magnetizing is practical.

Sorry, 6% overvoltage it is not overvoltage at all. Since it is an induction motor the current will be less 6% at such "overvoltage" [not more 20%- in order to start an overload relay].