Iacdrive|Automation Solution

Techniques contribute in control system

1. Any successful methodology is not a simple thing to come by and typically requires a huge commitment in time and money and resources to develop. It will take several generations to hone the methods and supporting tools.

2. Once you get the methods and tools in place, you then face a whole separate challenge of indoctrinating the engineers in the methods.

3. Unique HMI text involves a lot of design effort, implementation, and testing.

Many of the techniques contributed by others in the discussion address faults, but how do you address the “normal” things that can hold up an action such as waiting for a process condition to occur, such as waiting for a level/pressure/temperature to rise above/fall below a threshold or waiting for a part to reach a limit switch?

Some methods allow for a text message that describes each step. When developing these text messages, I focus on what the step’s transition is waiting for, not the actions that take place during the specific step. This helps both the operator to learn the process as well as diagnose what is preventing the machine from advancing to its next step.

I have seen sequencing engines that incorporate a “normal” step time that can be configured for each step and if the timer expires before the normal transition occurs, then you have “hold” condition. While effective, this involves a lot of up-front development time to understand the process and this does not come cheaply (with another nod to John’s big check!).

(Side note on sequential operations: I have used Sequential Function Charts (SFCs/GRAFCET) for over 20 years and find them to be exceptionally well-suited for step-wise operations, both from a development perspective as well as a troubleshooting perspective.)

I have seen these techniques pushed by end users (typically larger companies who have a vested interest in standardization across many sites) as well as OEMs and System Integrators who see these as business advantages in shortening development, startup, and support cycles. Again, these are long-term business investments that require a major commitment to achieve.

DC Drives QUIZ

1. List three types of operations where DC drives are commonly found.

2. How can the speed of a DC motor be varied?

3. What are the two main functions of the SCR semi conductors used in a DC drive power converter?

4. Explain how SCR phase angle control operates to vary the DC output from an SCR.

5. Armature-voltage-controlled DC drives are classified as constant-torque drives. What does this mean?

6. Why is three-phase AC power, rather than single phase, used to power most commercial & industrial DC drives?

7. List what input line & output load voltage information must be specified for a DC drive.

8. How can the speed of a DC motor be increased above that of its base speed?

9. Why must field loss protection be provided for all DC drives?

10. Compare the braking capabilities of nonregenerative & regenerative DC drives.

11. A regenerative DC drive requires two sets of power bridges. Why?

12. Explain what is meant by an overhauling load.

13. What are the advantages of regenerative braking versus dynamic braking?

14. How is the desired speed of a drive normally set?

15. List three methods used by DC drives to send feed back information from the motor back to the drive regulator.

16. What functions require monitoring of the motor armature current?

17. Under what operating condition would the mini mum speed adjustment parameter be utilized?

18. Under what operating condition would the maxi mum speed adjustment parameter be utilized?

19. IR compensation is a parameter found in most DC drives. What is its purpose?

20. What, in addition to the time it takes for the motor to go from zero to set speed, does acceleration time regulate?

Industrial Ethernet vs. Fieldbus technologies

Where we really need digital communication networking, in my personal opinion, is down at the sensor/transmitter and positioner/actuator/valve level to take the place of 4-20 mA and on/off signals. Down at the level 1 of the Purdue reference model you need a fieldbus, not one of the “H2” types of fieldbus, but one of the “H1” types of fieldbus. When first introduced, these technologies were not as fast and not as easy to use has they could have been, but after many years of refinement these technologies are finally becoming sufficiently easy for most plants to use.

An “H1 fieldbus” is the most practical way to digitally network sensors/transmitters and positioners/actuators/valves to the DCS. Options include FOUNDATION fieldbus H1, PROFIBUS-PA, CompoNet, ASI, and IO-link. These protocols can take the place of 4-20 mA and on/off signals.

Note that “H1 fieldbus” should not be confused with the very different “H2 fieldbus” category of protocols used at level 1-1/2 of the Purdue reference model to connect remote-I/O,

Operate low speed generator and high speed generator in the same terminal

Can we operate low speed generator and high speed generator in the same terminal? Is there a mechanical effect?

First, specify that this is an isolated system with two generators feeding the same bus. Operation of an isolated system is different than a grid connected system, and the mode setting of the governors have to be set to accommodate this. Depending upon the prime mover type and governor model, improper tuning will manifest itself in speed variations. The size of the two machines relative to each other, as well as their size relative to the load, can have measurable impact as well. The best way to tell whether it is mechanical or electrical in nature is to look at the time-frame of the phenomena relative to the time constants of the various control and response loops.

Second, “…In large power system, generators are not connected in the same terminal…” is not generally true, there are many power plants where multiple generators feed the same bus before the power is utilized.

Third, “…frequency oscillation is about 1.5-2 Hz…”, if you mean that the frequency swings between 48 and 52 Hz routinely, that usually indicates a governor setup/tuning problem or a non-uniform load.

Fourth, reactive current compensation takes place in quadrature from real power and should have minimal effect on real power and only affect the terminal voltage if not set properly. Droop compensation is the means for ensuring that the AVRs do not fight with each other since you cannot have two independent controllers attempting to control the same control variable.

Fifth, regarding different types of prime movers, some are inherently more likely to induce mechanical vibrations, especially reciprocating engines, especially if they are not all of the same size and/or number of cylinders. The same is true of the loads, non-uniform, cyclic loads can cause very severe problems especially on isolated systems where the load is a significant percentage of the prime movers’ output power. The analysis of, and solution to, such problems is an interesting area of study.

Power industry engineers

The power industry has many tentacles. Energy production is one key subset, the design, manufacture, installation and operation of hydro, nuclear, fossil, renewables, etc is continuing to grow especially in the renewable area. Then there is the transmission of energy which includes the design/manufacture/construction/maintenance of substations, protection and control systems, overhead and underground lines, series and shunt compensation, etc. Last there is the distribution of the energy to the customers at the lower voltages which includes many of the transmission opportunities but introduces other niche areas like power quality, smart metering, distributed generation, etc.

It’s not as simple as stating you want a PHD in the power industry with hands on experience without first knowing the ins and outs of the business. As has been previously mentioned, get your BS in EE with a slant toward power. Get a job in a utility and learn the business top to bottom so you can actually make an intelligent decision on what area of the business floats your boat. Once you know that then pursue an advanced degree in that specific area (the real bonus is most companies will pay for it).

UPS systems commissioning test and inspection procedures

The UPS systems commissioning test and inspection procedures are to conform to;

• BS EN 50091-1:1993 – Specification for Uninterruptible Power Supplies (UPS). General and Safety Requirements, AND

• IEC 62040-3 (Draft Edition – 2) in particular the Efficiency test procedures outlined in its “Annexure-J”.

These procedures to include:

1. Visual Inspection:
a. Visually inspect all equipment for signs of damage or foreign materials.
b. Observe the type of ventilation, the cleanliness of the room, the use of proper signs, and any other safety related factors.

2. Mechanical Inspection:
a. Check all the power connections for tightness.
b. Check all the control wiring terminations and plugs for tightness or proper seating.

3. Electrical Pre-check:
a. Check the DC bus for a possible short circuit.
b. Check input and Bypass power for proper voltages and phase rotation.
c. Check all lamp test functions.

4. Initial UPS Startup:
a. Verify that all the alarms are in a “go” condition.
b. Energize the UPS module and verify the proper DC, walkup, and AC phase on.
c. Check the DC link holding voltage, AC output voltages, and output waveforms.
d. Check the final DC link voltage and Inverter AC output. Adjust if required.
e. Check for the proper synchronization.
f. Check for the voltage difference between the Inverter output and the Bypass source.
g. Perform full-load, step-load, and battery discharge tests using supplier furnished load bank.

Why your project failed?

I have contracted with lots of different groups and moving within the same company to save failed projects or project in trouble or impossible to implement and helped these groups to achieve company goal. What I have noticed is that less the managers or groups know less they realize more knowledge or experience can help them. Less they know, less they understand they need help because they don’t know what they need. They think they are just fine until it is too late and a group or company goes under because of it.

I give you an example of one of the project I worked on at Nortel. I was assigned to write project specification for a product working with a director group with 100 designers and testers. During my research to get information to write the product specification I discover deficiency in the hardware they wanted to use that would cause the system reliability and availability unacceptable to the customer and did not meet customer requirement. I proposed design change in one of the interface card and firmware used in the system. The management did not agree with me on this item so I refused to write the specification the way they want it to not expose this deficiency. We had a large meeting with the president of the company with 20 people in that meeting looking at two different presentation to see if they need to change direction or stay on course and move me out of the way to another project activity. I am not the greatest in politics and making things look good when they are not.

The result was that I was moved to different project for 1 year implementing and releasing one more product that made the company lots of money. After a year development, they complete the project and released it to the customer. The customer starts validating the product and had lots of the test cases failing in the area that I proposed to change.
This was a large project and lots of money involve. The customer rejected the product and they went back on the drawing board after getting lots of this equipment on order for this project. The management came back to me and one of my team members to come back to the team and help.

Me and my team member both having experience over 15 years at that point came back and have a solution designing a new complex interface card with microcode firmware and some software to save the project. I and he had to work for 4 months for day and night having design review between two of us at 3 am in the cafeteria to get it done (defining specification to validated working product).

This project was completed and customer accepted this solution. The director group was dismantled and all people in the group were laid off and absolved in other groups in the company and some in the same group. The management groups were smart people with good intention, they were with software background and good intention for the project. They just did not have the knowledge and background to manage the system and hardware level because of lake of knowledge and experience in that area.

You see this in lots of companies when a software designer or manager is successful in their area, they get promoted and manage groups that are out of their area and lots of time they destroy groups or project because of not having the background to identify good or bad direction to go. You will always have engineers to not agree with each other and managements have to make decision to go one way or another. The wrong decision in these cases can destroy a project or company. Not all engineers can present a case in 1 hour to sell you their point of view, Remember they are not lawyer or sales man, they are engineers. So what do you do, Follow the sales man or lawyer to save your project or the reason to drive your decision and if you don’t have the knowledge or experience to lesson to the reason then you will make the wrong decision.

Solar power

On a purely theoretical level and ignoring interrelated economics and energy usage, it makes sense to charge EVs during the day – though never in non-distributed environments, IMO.

In reality, and the reality for likely the rest of my life, it makes more economic and particulate emissions sense to distribute solar power during the day to decrease, and ultimately decommission, fossil fuel sources used for peak demand supply that occurs during the day.

Thus, using solar output distributed to offset the dirtiest, most expensive and most distribution grid loading power enhances and optimizes the value and worth of that solar generated power – both economically and ecologically. Attempting, therefore, to do all of ones’ EV charging off peak is the optimal solution until the mix of energy sources changes dramatically – likely a 20 plus year process even in the most environmentally friendly “energy generation mix” regions of the world. Even if one charges during “peak”, it is better to simply charge from the grid as the distributed energy is allowed to go to areas of peak demand. Again, for at least my lifetime, I don’t project a more optimal use of that generation even assuming the archaic state of most “grids” persist.

Right now, even for a 1 story commercial building, solar cannot supply the energy needs used in the office, much less a manufacturing facility. In fact, it can normally only supply 1/3 or less for the most energy and resource intensive commercial environment in a UV intense region (and that is quite an optimistic calculation, more likely 1/5th). Once you get to two or more stories on the building, one is not even close. On a modest tower with a tower parking garage, the footprint is likely to small to even generate the needs on a theoretical basis. Distributing the energy to location of greatest needs will allow us to dial down and decommission peak sources, which again are the dirtiest and most wasteful.

At some point, we will hit a new equilibrium where the energy generation mix is much cleaner, solar generation specifically is much more efficient, and peak power generation is handled more efficiently and ecologically cleaner. I still believe, however, that distributed power is better than “off grid” type of scenarios as it allows the energy to go where it is being demanded at the moment, decreasing the need for redundant sourcing. And, even in the cleanest energy generation mix, redundancy means building more of something and is by definition more energy wasteful and ecologically wasteful than a scenario where the redundancy buffer that is required is lesser.

Much of this type of debate reminds me of the consumer sort recycle versus the destination sort recycle debate. Even with the advances in trash collection and recycling processes, 20 years later we are suboptimizing the recycling process. Much of the reason for that is the “style” statement, making people feel like they are contributing by sorting themselves. It may make some people “feel” better by imagining “independent” off grid or semi off grid solutions. In reality, however, we live in an interconnected world where “sharing” or distributing solutions to leverage scale and minimize redundancies is far more advantageous, economic, and a faster route to a solution to both particulate emissions issues and energy independence for groups of people.

Cleaning solvent for motor windings

Usually, the dry ice approach is the best bet because it leaves no real residue from the cleaning material. If the insulation is “fluffing”, the likely problem is that the air pressure used to move the dry ice particles is too high.

A second alternative that can be used is “corn cob blasting”. The media is reusable, biodegradable particles of corn husks. Again, a relatively low pressure air stream is required. It WILL damage the insulation if the pressure is too high, just as in the dry ice case.

Most solvents will aggressively attack the insulation systems used for windings: this is specifically true for the larger machines where mica tapes are coated / filled with a resinous material (vacuum pressure impregnation). However, it is equally true for smaller machines where the primary insulation is at the strand level and is essentially a varnish or enamel coating on the wire. If you’re worried about how the solvent will affect the insulation system, get in touch with the motor supplier for their suggested approach.

If a solvent-based cleaner must be used, it should be applied sparingly – BY HAND – on the areas to be cleaned to break up the oily / greasy contaminant and then rewashed with some other (non-solvent) approach to clean away any solvent residue. This also will require a “dry out” of the equipment after the second washing. This three-stage approach tends to minimize damage done by solvent that may be left behind to “eat away” at the varnishes, enamels, and resins comprising the insulation system.

One last thing – pretty much ALL solvents are going to be designated as hazardous materials in most regions, due to health concerns. Therefore it is more a case of “pick your poison”!

Negative Impact of Accelerated Depreciation on the Indian Economy

For argument sake or as an illustration, if we assume that 1 MW solar will generate 1.6 Mkwh and rs. 1.2/kwh is rebate for AD taken by the investor = 16 x 1.2 = Rs. 19.2 lakhs/year

[Now, Adani and Tata Power have been negotiating the firm Contract PPA to get more, like wise biomass people who based their PPA on LCOE, but, are asking more money from Government, hence, Solar PV developers may also follow the same route after few years, wherein this rebate of AD given will not have any meaning!!]

Total rebate given = 19.2/year x 25 years = Rs. 480 lakhs = Rs. 4.8 Crore (that too year wise depreciated / devaluated rupee value, which has no meaning !)

But, the tax saved is = 80% of investment = 0.8 x 10 cr = 8 Crore, upfront, right in the first year, which is great value, which government would have used as Equity to develop many more MWs.

Is this POLICY of providing 80% Accelerated Depreciation correct by any standards and why Finance Secretaries or policy makers can’t take note and issue corrective measure for INDIA FIRST Culture??

MNRE, in its Draft policy has proposed 20 to 40% Viability Gap Funding, which will further worsen the LOSS to the government !!

If Mahagenco (with 50% subsidy) goes ahead with the proposed business model, then, how and why State and hence Central government has to take the burden due to such errant policies??
We must put an end to the Scrupulous Project Development, which avails the Capital Subsidy (or Viability Gap Funding) and the Accelerated Depreciation and then the Promoters Sell the Project to a prospective buyer, who in turn approaches the Government for the Tariff hike in the 25 years tenure (please note the Politics dynamics or change of administrative set up will hamper the sustainability), thus, the nation is a great loser

Policies and the enabling tax advantages to few promoters (who claimed Capital Subsidy without creating good quality asset or with NON functional biomass power plants) have made a big dent on Indian Economy without any good results esp in Renewable energy sector.

Government or its administration through such policy (without checks or being accountable) transferred the Public Property to the Private Companies in the Form of Renewable Energy Generation through Capital Subsidy (or Viability Gap Funding) coupled with Accelerated Depreciation along with Low cost Debt fund to these Corporate companies (like EXIM etc) / Project Developers – entrepreneurs, which are not paid back as few of these projects are not functioning and still no action taken to recover the Capital Subsidy paid or Tax recovery which was availed through Accelerated Depreciation (AD).

If Government would have established all these projects from the Tax collections (which are doled out as free through AD), it would have needed only a fraction i.e only Rs. 51,504 Crores, which could have been managed from the taxes of Rs.137,344 Crores while retaining the land and property in Government’s name and could have generated lot of employment.

But, by giving an opportunity to Private sector, many have failed to deliver and no Action to recover the Capital Subsidy or the Debt (due to Tribunals etc…. Please be informed that Indian Parliament had to pass an act in Dec 2012 to recover debt (through wrong business cases of Project Promoters, approved by many banks which were certified by National and International Advisors or Consultants) which is around a whopping 40 Billion USD!!)

Total estimated Renewable energy project capacity = 12% of total installed 220GW = 26000 MW
Cost/ MW Investment Equity Debt Cap Sub AD
Source MW installed Total 30% 70% Rs(Cr) 80%adj
Biomass 6 4,500 27,000 8,100 18,900 6,750 21,600

Wind 7 20,160 131,040 39,312 91,728 104,832

Solar PV 10 1,300 13,000 3,900 9,100 VGF? 10,400
(Ground)