www.ppkportal.com

Dear Friends Happy to inform about the launch my new website. The website will be officially active January 2016 onwards Expecting your valuable support and good wishes www.ppkportal.com

Industrial Networking : OSI Reference Model

Osi reference model from prashob7

Industrial Automation : Basics of Profibus Network

Profibus from prashob7

Energy Savings Using AC Drives

Energy savings using ac drives [autosaved] from prashob7

Industrial Automation : VFD In Jaw Crusher Applicatoin

Now a days VFDs are quite often used in Crusher/Mining industry. Here in this post the use of VFD in crusher application especially in the case of Jaw crusher is being mentioned.
in rock crusher plants induction motors are used in

• JAW CRUSHER : often coined as primary
• Cone Crusher : often coined as secondary
• Screen
• Conveyors
• Vibrators   : often coined as feeder motors
• lube pumps
• slurry pumps

For all of the above mentioned loads, now a days VFD is used. For each load characteristics are different.

JAW CRUSHER

Here as you can see from the above animated picture, the size of the rock , hardness varies by big margins, and hence heavily fluctuating load is there
the entire torque is provided by the giant flywheel attached.

Operating Strategies
Since the load is continuously varying, there will be situations where the rock get stuck and the drive needs to be under inching/jogging mode and operator has to jog the drive forward and reverser a few times to clear the rock out.

also there will be many a occasions where the motor current limit will be exceeded.

I  have seen in many occasion where the drive supplier provide a higher rating drive to ensure failure free operation. but its unnecessary

In the case of jaw crusher vfd you have to ensure follow things
 

• VFD always should be configured in vector/torque control mode

 

• Crusher sites are often dusty, so ensure a good enclosure of higher IP rating

 

• Check whether the motor is of inverter duty or not, always keep an eye on motor temperature

 

• If supply for VFD is from Diesel Generator, then verify whether the diesel generator is sized so that its able to meet all the peak load conditions appearing, please ensure no drop in voltage is taking place in that case.

 

• When designing a panel do put option for jog forward and reverse, provision for monitoring load current and also remote control desk.

 Setting relevant parameters for drive

when configuring the drive on vector mode ensure

proper motor data identification is performed
do cross check the upper and lower torque limits sets
ramp times set
check the current limit set
do all the relevant optimization sequence available in the drive so that maximum performance is available
do check the response of drive in the event of fault or power dip or abnormal condition

and most important do explain the working, purpose and operating of drive to the concerned operator because often unawareness is what leads to disasters

 In the next post i shall put the drive performance curves, typical application example for crusher related case

VFD Panel : Protective Switchgears

In my Previous post I just have mentioned the basics fundemental facts regarding AC Drive panel
In this article is shall discuss

• the various protective switchgear available 
• what all configuration we can opt
• how to choose protective switchgear

Isolation
Mainly in almost all industries there will be a MCC panel for various motors installed. When separate drive panel to be provided a power isolation to be included in the panel
mainly we have following options

• SDF
• ISOLATOR
• MCCB
• Power contactor

 Now Using SDF is convention practice, but now a days customers prefer MCCB to SDF. While ordering MCCB should also order the door mounting kit if you want to operate the device from door.

Now is the incomer supply needs to be controlled remotely then we use Powercontactor and it is switched by proper control loop.


Semiconductor Fuse

For Power Electronics based switching devices it is always good to include
thyristor fuse at the incomer. Now when compared to HRC fuses, thyristor fuses are much more costlier.

while ordering fuse, you have to be careful in selecting fuse and its base.different type of fuses are available in the market.

most of the manufactures in their vfd catalogue have mentioned the details of
appropriate switchgear to be used along with particular drive. once you get the specification you can opt for different make if price does matter

I shall include some selection chart in the next post and shall explain with examples  " how to select right switchgears"

Designing AC Drive Panel: Basics

VFD/Inverter panel  essentials


In this post I shall enumerate the basic requirement, design aspects, electrical aspects of vfd panel

we all know that now a days with the extensive developments in the field of power electronics
now vfd application to induction motor is now a common practice. Now in the market application specific drives are available with sophisticated control features.

Now whatever the drive make is , there is some general standards to be followed for
selecting the right switch gear
selection of filters, reactors and smoothening circuits
cable sizing
cooling clearance
arrangement of modules
panel cutout
glanding
control wiring etc
We can supply the panel with the way we want. But its not the right method. One who designing the entire system should have a good knowledge
motor load type/ Application
Ambient conditions where the motor and panel will be fixed
Total distance of power cabling
The way the cable to be routed
The IP standard to be followed

While executing the project the concerned engineer must understand client's exact requirement and should prepare the drawings and layout based on that.
Now even though the drive has got inherent ability to respond to faulty conditions, its always recommendable to go for protective power components. The most common include

sdf/mccb at incomer : mainly meant for supply isolation

HRC fuse
Thyristor fuse
Line reactors, Line LC Filters
Output reactor : if requred
Braking components : if required
Power cable selection


Line reactor selection

The equation for the reactance of an inductor is
XL = 2¶FL. Where XL is inductive reactance in Ohms, F is the applied frequency of the AC source and L is
the inductance value of the reactor. As you can see, the reactance and therefor the impedance of the
reactor is higher with a higher inductance value. Also, a given inductance value will have a higher
impedance at higher frequencies. Thus we can say that in addition to limiting the rate of rise in current, a
reactor adds impedance to an AC circuit proportional to both its inductance value and the applied
frequency


Now while selecting the filter components you should be always careful because wrong selection will result in adverse results, but from my past experiece what I understand is that if you once got the concept, if you know the electrical aspects then you can go ahead.

since the inductance is in series in the power circuit  ofcourse a small percentage of the applied voltage would drop across. 
the drive manufactures in their product catalogue mostly mentioned the specification of the suitable line reactor.
once you got the specification you can check for other make too.

This topic is not over, shall update further in coming days
those who read, if find that the post is informative please provide your valuable feed back. this would certainly help me in improving over the upcoming posts