"Current" less water !

In the early sixties,a major Hydro-electric project was set up known as Bhakra Nangal Project.The concept of generating electricity from river was rather a novelty to the local community.The farmers in the surrounding regions were dependent upon water from the downstream of the project.

A group of farmers felt that there was a fall in the yield of the crop in their fields in the year immediately following the year of the commissioning of the project.They came up with an idea that the fields are being supplied with "sapreta"( a local term usually used for milk from which fat has been removed i.e. toned milk) water. The feeling was that "current"or "essence" has been extracted from the water rendering it "ineffective and incapable" of nurturing the crop leading to a drop in the yield.
As bad news travels faster, a panic like situation was created amongst the local community which could have culminated into a major agitation.

Fortunately local leaders intervened and explained the matter to the agitated farmers and thus a major crisis could be averted.

Meters without pointers !

I got a call and the caller sounded frantic. Normally, he is a very composed person and an extremely efficient store keeper. He explained to me that there was an inventory audit going on and the auditor was refusing to believe that the material shown matched its description. Not only that, he was threatening to report the matter to the higher ups. Ah, that was serious.

I walked over to the store and found that I knew the auditor because he had audited the inventory of equipment in my department - Quality Assurance, the previous year.

After the initial pleasantries, I asked him what the problem was. He became serious again and told me that the storekeeper was showing some tiny little stuff as potentiometers. I looked at what was offered and said that they were indeed potentiometers. He looked puzzled and asked me, "Then where is the pointer? Don't all meters have pointers?"

---- J.L.Anil Kumar

Transformer Transformation

During the early part of my teaching career, I joined an engineering college near Bangalore and took over as the Head of ECE department.
There was an immediate requirement of 12 Nos. of small transformers for the laboratory. I was informed that the procedure called for taking the indent personally to the Director of the institution (a non technical person), who would scrutinize the indent and authorize the ordering.
This Director had a reputation for being very strict and abrasive. This being my first encounter with him, I entered his chamber with great trepidation.
He scrutinized the indent and read the title “Transformers-12 Nos.”
He thundered, “Do you know what you are asking for!!! ”
“Y-Y-Yes Sir”, I mumbled.
“Do you know what would each transformer cost? ” he continued in the same tone.
“Er….. about Rs.30/-, Sir.”
“What!!! Do you take me for a fool? Do you think you technical people can take me for a ride? Do you want me to believe that those big units that I daily see when I ride to college could be had just for Rs. 30/- .”
I immediately understood the situation. For him, transformers meant the large distribution transformers one can see installed by the road side.
“Sir, if I may clarify, these are tiny transformer units meant for use inside our laboratory.”
All of a sudden the tone of the Director’s speech changed. He appeared mellowed and embarrassed and said “Ok, please go ahead and order 24 Nos. if you want. I am all for giving you technical people full freedom in your activities.”

------ K Sudheendra

"Geared-down" to troubleshoot !

It was one of my earliest commissioning assignments. The job was ideal for a rookie. Just a 45 kW dc drive with very simple functionality. Start, stop and speed set potentiometer. The control panel was built with care and installed properly. All I had to do was to conduct routine checks and start the drive return home.
Cochin Kadalas (Kadalas means paper in Malayalam-Kerala, India) was the factory in which I had to do all this.
Everything went as per expectations. The only hitch was that the place was so hot and humid that, half an hour after I started my work, I looked as if I had fallen into a pool fully clothed and got out. I was sweating so profusely. When it became impossible to bear, I took my shirt off and that is the only time I have conducted official work so dressed, I mean, undressed.
When it was sure that the drive and the paper machine to it was driving were working as expected under no-load, paper pulp was made and conveyed to the machine. As soon as the pulp entered between the rollers the machine stopped. The ammeter indicated full rated current. I opened up the panel and increased the current limit to the rated overload limit. No change. The machine refused to work.
All kinds of investigations followed. But the situation did not change.
The machinery was installed by a man who barely spoke Hindi. All he knew was Bengali. With my broken Hindi and more broken Bengali, I tried to find out more about the machinery, with the hope of finding out the reason for the stalled machine. While we were having this conversation, he commented that he had very recently commissioned an identical machine successfully. I tried to interrogate him to find out if there was even a minor difference between that and this machine. He kept insisting that there were none.
While all this was going on, he let slip that the motor in the earlier case was a 750 rpm machine and that this one was ‘unnecessarily’ 1440 rpm.
Ah ha! The gearbox between the motor and the machine was also exactly as in the previous case.
Now it was clear that the motor was delivering half the power required because it was running at half the speed!
I had a tough time convincing the non-engineers that we either had to change the motor or the gearbox. Finally the latter was done and my one-day-assignment ended after nearly a week.

------ J L Anil Kumar

Problem ---- watered Down !

My uncle told me this story from his own experience, a long time ago.He was a consultant to a beer manufacturing unit. The unit installed a new bottling plant and tried a dry-run. Everything went well except the bottle capping part. Bottle after bottle passed and the machine refused to cap them. After days of checking everything repeatedly, the man in charge sent for him.After taking a good look at the machine and how it operated, he placed a beer bottle filled with water. Promptly the machine capped it. The machine had weight sensors and was designed not to cap empty bottles !

-- J L Anil Kumar

Link to humour

Here is a link to an interesting site on humour http://www.csrstds.com/humor.html

THE (UN)COMMON SENSE

About 6 years ago I had to set up servers for my colleague at
a laboratory inside ALTTC (Advanced Level Telecom Training Centre),
Ghaziabad,Near Delhi. I hooked up the server, monitor, keyboard,
mouse and the works! I first switched on the monitor and next I
tried switching on the server but it refused to do so.

Based on my years of “on-the-job” experience, the first thing
I suspected was the SMPS. SMPS seemed to be order because the
power ‘ON’ LED on motherboard was on. Next, as a standard procedure, I pulled out all the peripheral cards, disconnected keyboard, mouse and all other
connections except the power cable and tried again.

 Still NO SIGN of server switching ON! 

   Due to non-availability of CRO or such other testing equipment,
I could not test the motherboard and called up the supplier and
told all the symptoms, who advised me to bring it to Delhi, as he
 did not have service centre at Ghaziabad.  Meanwhile, I called up
 our Delhi office to borrow another server and after some initial
reservation they agreed but asked me bring along the ‘faulty’ server. 

 We confidently connected power to the new server! But, still no sign
 of life!

 NOW I was really at my wit’s end! My whole confidence was at the
lowest ebb! By now it was late in the evening. Completely exhausted,
on an impulse I checked the supply voltage. It was 110V AC instead of
normal 220V AC, which one would normally expect. (We later found that
a special supply network of 110 V AC had been created for these
equipment supplied by Fujitsu, Japan.)

   But why did the monitor switch on at 110 V AC? Well it turned out
that the monitor had higher voltage tolerance range.

  Even today the remark of my boss keeps ringing in my ears “ Gana, 
sometimes you need to stop using too much of brain!”

 ---------   R. GANAPATHI RAO
Research Associate,CENTRE FOR DEVELOPMENT OF TELEMATICS,
ELECTRONICS CITY,BANGALORE.

Drilling Machine Drills

Drilling machine mystery

Our ½ hp, 3ph, drilling-tapping machine is 10 years old. Recently, the 6A HRC fuse in the R phase blew, followed by tripping of the upstream ELCB.

Could it be an earth fault? Ohm-meter did not indicate any visible earthing. I tried hard but could not trace the fault physically. I just replaced the fuse. The machine operated without problems for few weeks.

Wonderful!

And then the fuse blew again. Well, I reckoned it could be just a transient phenomenon.

Cleaned up the electrical panel. Replaced the fuse. No problem.

After about 10 days the fuse blew again, followed by tripping of the ELCB.

Now I was getting really mad. Opened up the incoming R-phase cable terminals at both ends (about 4 meters). Checked with a “Neon tester’ and it glowed gracefully. Cable must have got shorted inside. Changed the cable. Replaced the fuse. Now the machine was running perfectly. But strangely there was no tell-tell sign of burn mark in the old cable.

After about a week the drama was repeated. This time, without much ado, I replaced the R phase fuse with a 16A HRC fuse.

After about a week, there was a flash at the incoming terminal box of the drilling machine.

The Fuse blew, ELCB tripped.

But I was more than happy. I had found the culprit. The incoming screw holding the Terminal Block had fouled with the terminal of the R phase.

Another lesson. Neon tester had been showing capacitive voltage.

--- P. K. Ray ----

raynar.industries@gmail.com

Insulation Value Crisis !

I was looking after the erection and commissioning of electrics at Bhilai Steel Plant (Site : Rajahara Mines) in Central India in the early sixties. Massive construction activity was on. The plant was being set up with the assistance of the erstwhile USSR.

A high-tension slip ring induction motor of 250 KW for driving a cone crusher was to be installed. The standard practice is that the insulation levels are checked and only when the IR (Insulation Resistance) value is more than several Mega ohms, the motor is energised.

On initial checking, the IR value was found to be much less than 1 Mega ohm. This was not considered unusual as the motor was shipped from the USSR long back and during several weeks of transportation and storage, moisture could have seeped in. As a standard remedial measure, the motor was put on heating, initially by external means and later by passing a current in the rotor of value higher than its rated load current. The motor was placed at its final location, which was about 25 meters below the ground level, in a pit. Since it was very cumbersome to get down into the pit every time to measure the IR value, the Meggar was kept at ground level, and a set of cables was sent down into the pit and connected to the motor.

The heating was started and, after every one-hour, the readings were taken. We were surprised to note that the IR value continued to remain low. After several rounds of heating, the result was the same much to the annoyance of the commissioning crew, and adding to the perplexity of the engineers.
Experts from the USSR were also at a loss.

The situation became very critical when it was known that the plant commissioning date was fixed just after 3 days to coincide with the visit of the then minister of Steel and Mines.

After many hours of lost sleep and anxiety of the team, it occurred to me to go down to the pit with the Megger and check the IR value connecting the Megger leads directly to the motor terminals. And lo, the value indicated was more than 100 Mega ohms, which was perfect! The readings were taken many times to ascertain that the values were consistent!

After analysis, it turned out that some one, while searching for a cable of suitable length, found an L.T. 3-core cable lying around, and 2 cores of this cable were used. Since the megger was a 10 kV HT Megger, it was measuring the insulation resistance between two cores of a low-tension cable. Even though the motor at the end of the cable had attained high insulation resistance after heating, the lead insulation itself was much lower and naturally the lower value was being indicated by the Megger. The Megger was measuring the inter-lead insulation and not the motor insulation value.

The team could then energize the electrics successfully and celebrated with a shot of vodka!

-------- Raghavendra Girimaji.

"Kickbacks" of the Electrical kind

We all know that an “inductor resists change in the current flowing through it”. We also know that when there is a change in the current through an inductor, it gives rise to an inductive kickback. We put freewheeling diodes across dc relay coils or we stick a snubber across ac relay coils and so on.

I realised, with a shock (quite literally), the possible magnitude of this kickback.

In the early part of my career, one of my responsibilities was to test the incoming materials. This included some HT transformers too. One of these had two secondaries, one star connected and the other delta connected. These supplied diode bridges that eventually supplied a twelve-pulse output used as the anode supply in a large RF induction heater.

I was still learning my ropes and I had to test one of these transformers for the first time. I decided to first measure the winding resistances and see I they matched the specifications. I connected the probes of an analog multimeter, set to measure resistance, across the secondary. To make the connections, I held the probes of the multimeter to the terminals by hand. Since the winding inductances were fairly high, the needle started its sluggish motion and I realised that I had set the range wrongly. I removed the probe held in my right hand and I was in for a shock! The small dc current that the meter had already driven into the coil was interrupted and this generated such a kickback that my left hand flew, still holding the probe. That pulled the meter attached to it from its precarious perch on the transformer and sent it crashing to the floor.

So, this is what an inductive kickback “feels” like!

Many would not believe me when I told them this story. However, if I asked them to try it for themselves, there were no takers!

---- JL Anil Kumar.