The largest TBM company in the world is Herrenknecht in Schwanau Germany. Trey and I were privileged to visit their facilities earlier this year, and it was a fascinating experience. The image on the right is the entrance to the plant, and the concrete circles are actual casings from one of their various world-wide tunnel projects.

We seldom see these giant machines out of the ground, and within the tunnels it’s difficult to get a perspective on the entire machine.

While in Germany, we were able to actually walk around and inspect a complete machine. No one seeing one of these behemoths in clear view can help but be impressed at the genius of Martin Herrenknecht when he developed this technology and formed Herrenknecht in 1977. To say the least, they are engineering marvels.

Tunneling through various types of earth is challenging, and Herrenknecht has developed great expertise in this area.  Sometimes in soft earth, they must pressurize the cutting head area,  and anyone needing  access to that part of the machine must enter via an airlock system.  Similar to deep sea diving, the workers can only stay there for a short period of time, and must endure decompression chambers upon exiting. Very careful geologic analysis is required and the engineers have to be prepared for penetrating large pockets of water in addition to the various types of soil, sand, and rock.

In addition to air pressurization, the machine must often inject materials at  high pressure  into the earth surrounding the cutter head to avoid a collapse.  Once the head of the machine passes, prefabricated concrete walls are installed to shore up the tunnel. TBMs do NOT back up well, so it’s imperative that great care be taken to insure that the machine doesn’t get stuck or off course.

One question often asked, is “how do they keep this huge machine going in the correct path?” (Keep in mind, that it isn’t uncommon for two machines to be starting at opposite ends and tunneling toward each other, so precision is necessary. )

They do this by carefully using lasers on a frequent basis to check the path, and by making minor adjustments to the cutting head.  As we’ve often noted here at EMA, astonishing feats of engineering are commonplace at Herrenknecht.

The motor drives are specialized large horsepower VFD s  manufactured by Schneider Power Drives in Austria.  We were also privileged to visit Schneider early this year.  Schneider Power Drives is a high quality company with very skilled people, of whom we think  highly.

EMA has been blessed to have a great relationship with both Schneider and Herrenknecht, and we’re proud to serve as the north American service center for both. It’s not just quality equipment that makes great companies; it’s great people. We find that to be true for both of these companies; friendly, results oriented, and competent are the best descriptions of the folks at both Herrenknecht and Schneider Power Drives.

TBM service calls are usually performed under ground, sometimes, several miles into the tunnel.  You often enter via a vertical shaft, and then climb aboard a special locomotive used both to transport personnel and equipment.   The materials generated by the tunneling, are either removed by a long conveyor, or are liquefied and pumped out.

The motor drives can be either air-cooled or liquid cooled, and are usually high horsepower open loop vector drives.  There are both variable and constant torque loads, and while at times the units are readily accessible for service, at other times, the working space is very tight.  TBM service is not a place for the claustrophobic. Downtime is very costly on a TBM, and so a quick and efficient response is necessary.  The tunnel operators often stock spare parts, and additionally, we keep parts here at EMA.

While not widely known, TBMs are at work all over the world.  Since TBMs can construct large tunnels with very little surface disturbance, it’s possible for even those near the vicinity of a tunnel project to be completely unaware of the machine’s presence.   TBMs are an economically and environmentally attractive solution for utility, traffic, water and sewer construction, and they’re more and more becoming the standard way to construct tunnels in urban or environmentally sensitive environments.  Because TBMs don’t use dynamite, they’re safer, and for those living in the area of the tunnel, a better neighbor.

As we say..  it’s an underground business, but we like it!

To see a youtube video about Herrenknecht TBM, click HERE.

To begin the process  we had to figure out their program.  Whomever had done the original program was long gone, and factory support on a unit that old wasn’t an option.  We first found and purchased an old DOS PC with a 5.25 inch floppy port.  Using DOS 3.0 (remember that?) we  began looking at the original program.  Following a number of work-arounds we were finally able to see the ladder logic, of which the rungs, by the way, were unlabeled by the original programmer.

Following that, it took a few days of tracing and deciphering to completely understand and upgrade  the old code to something more modern.  We were then able to program a more standard AB PLC.  The original drive was replaced with a modern Yaskawa E7.

The folks at Cornell were pleased enough with the results to proudly point it out to some other university folks visiting their facilities area.

At EMA,  we strive to provide solutions and service, not just equipment and promises.  EVEN if it means rounding up an old DOS PC to decipher the problem.  We think our customers deserve nothing less.

On the most recent call, we discovered that 12 cooling fans were damaged, resulting in excessive temperatures building up on the input rectifiers.  The output IGBTs were fitted with thermistors, but the input hockey puck type diodes, did not have thermistors mounted on them.

This caused extensive heat damage to all of the input diodes. Additionally,   the long term effects of over-heating  damaged the bus caps(this is a very common failure with over-heating).  In bus capacitors damaged from heat,   the electrolytic dries up, and the excessive ripple on the  DC Bus results in poor performance, and additional heating.

In this case, we were able to repair the inverter, but in a similar case recently, the damage was just too extensive and we replaced the unit with another vfd.

Cooling and other environmental issues can become a problem on any horsepower vfd, but is considerably exacerbated in high horsepower units.   Annual preventive maintenance can allay many of these problems, and if downtime is an issue, then you should consider such a program.

EMA routinely works on many high horsepower applications and we’re accustomed to both preventing and repairing these problems.   We see many of these large drive applications in waste water plants, but not all.  Click HERE for your nearest EMA facility, or  EMAIL us to discuss these or any other drive and automation problems you may be having.

Mission 10:14, with the approval of village chiefs, is committed to providing one multi-person mosquito net to every family in the  two villages selected for the inaugural portion of this project.   Each net costs $13, and Mission 10:14 is guaranteeing that every dime of donations given to the Net the Village project will go directly toward purchasing a net.

Please consider buying one or more mosquito nets to combat the dread disease of malaria, with a tax deductible gift.  Checks should be made to Mission 10:14, and designated “Net the Village.”  Mail checks to 

Click HERE for the directory.  Keep in mind that EMA is a world class repair center for Reliance drives, and has experience on both old and new Reliance equipment.

So, what are they? Voltage transients are instantaneous bursts of high voltage, resulting from a rapid release of stored energy. This energy can be stored within the existing circuit, and released by switching action, or it can be external and injected by either capacitive or inductive coupling. Suppressing transients requires that the energy be dissipated at a voltage level low enough to insure survival of the circuit components.

The detrimental effects voltage transients can have vary from the destruction of power semiconductors, to computer glitches. Some transients are predictable, such as SCR commutation spikes, and are more easily suppressed. Some are random, caused by lightning, switching parallel loads, and other power system changes.

Random transients are more difficult to identify and suppress. It’s a standard joke among service engineers that one of the most reliable ways of suppressing a transient, is to have a service engineer connect a scope and look for it!

A sudden change in the electrical conditions of any circuit will create a transient voltage from the energy stored within the circuit inductance and capacitance. The rate of current change (di / dt) within an inductor (L), will generate a voltage (-L di / dt) which will attempt to keep current flowing in the same direction. It doesn’t last long, because the source of the energy is limited to what is stored in the inductance (1/2 Li squared), and is usually released at a high instantaneous power.

With this in mind, consider for a moment, what happens when a common transformer is energized, and then de-energized.

The step function of the energization is coupled to the secondary by the stray capacitance and inductance, and can generate a burst of voltage twice the normal peak secondary voltage. It’s also possible that regardless of of the transformer turns ratio, the secondary can “see” the primary voltage via capacitive coupling even though it may be many times the normal secondary voltage. (Worth remembering if you work around high voltage step down transformers)

Unless suppression is added, this transient will be placed across the load. De-energizing the transformer causes even more severe transients, due to the collapse of the transformer flux.

Other causes of transients are shorts, fuse blowing, and switch or contact arcing.

Several methods of suppressing transients are common. One is to filter or attenuate the transient. The filter captures the relatively high frequency transient, while allowing the lower frequencies to pass unhindered. The simplest and most used filter is a simple capacitor. Oftentimes, a resistor is placed in series to limit inrush, and this is the makeup of the popular RC “Snubber” networks.

Metal Oxide Varistor (MOV)

Another popular method is to clamp the transient to an acceptable level. The most common device used for this is the MOV or Metal Oxide Varistor.

External transients can be reduced by using shielded signal wiring, isolating power sources, running control and power wiring in separate conduits, and keeping connections tight.

All of which you already knew you were supposed to do, right?

Yaskawa in particular, has their intelligent pump controller, called the iQpump.   The iQPump is an all in one VFD and highly featured pump controller.  Almost anything you’d want in a pump controller, is here. That includes features such as an automatic anti-jam control, impeller de-scale, low city pressure monitors for booster pump systems, lube pump control, and constant pressure well draw-down control. It also has a built in process controller for controlling flow, pressure, or any other process variable.

The unit can operate either one stand alone pump, or you can network them to operate up to 8 pumps.  The software is free, and easy to use.

For those of us in the service business, the keypad reads in pump specific language, rather than what a normal VFD would read.  This is very helpful to both operators and service people.

The unit has also been designed to easily operate on a single phase input.  That’s especially helpful on rural irrigation systems.

These are interesting and useful devices, that we think the market is going to really like.  Yaskawa has a great reputation for quality, and these are very well engineered intelligent pump controls. EMA is proud to be  a distributor for the iQpump .  Click here to download a brochure on the iQpump. (be patient, this is a large pdf file)

Read an archived article about EMA and the irrigation business in Delta Farm Press.

The drive cabinet showed extensive arc-flash damage, evidently from a loose bolt, which had actually

Jon Blakeslee repairing the unit

exploded from the heat, melted the bus bars, and spread molten metal and components throughout the cabinet. The circuit boards and relays were badly damaged, as were the thyristors (SCR) in the power section. The manufacturer had been sold to another company, and they in essence told the customer that nothing could be done to repair this unit.

If this had been a smaller horsepower, or a less sophisticated application, we would have simply suggested replacing the drive, but due to the special motor and application requirements, that wasn’t a viable alternative.

So the decision was made to repair the unit. This required the tedious task of rebuilding a number of circuit boards in addition to repairing the power sections and the relay logic sections. Technicians from EMA New York spent long hours working on this,  and finally had it ready for site testing. Once testing began, they discovered that the motor shaft encoder was faulty as well. The encoder was an obsolete model, no longer available. EMA researched and eventually contracted with an encoder manufacturer to supply a modified encoder that would work on this application. (In LCI drives, the exact rotor position must be known at all times in order to facilitate the commutation of the power section.)

Once this was done, the 1000 Horsepower machine once again ran well.

These are the kinds of calls that really set EMA apart from many of our competitors. EMA technicians can rebuild large high capacity power sections, and at the same time, do the intricate troubleshooting and solder work necessary to repair damaged circuit boards.

But perhaps even more importantly, EMA doesn’t abandon customers when the equipment manufacturer tells them there’s nothing that can be done.   We can’t promise to deliver miracles, but our company culture really leans away from telling anyone that “there’s nothing that can be done.”   We’ll figure out some way to get that machine running again.   It’s one of the primary reasons we enjoy such a high customer satisfaction rating; the highest in our industry.

If you’ve ever read his bestselling book “How the Mighty Fall”  you know that he chronicles how companies go through five steps to failure..   the first step toward failure is one that has become a theme of mine recently..    “Success leads to hubris.. “ put more plainly..  our successes, both personal and professional, can lead to arrogance.  And within arrogance, are the seeds of our destruction.

In “Good to Great,” Collins chronicled how that truly great CEO’s shared a common trait..   humility.

This flies in the face of what we commonly think of as leadership, but Collins is not primarily a philosopher, he’s a researcher, and his data is inarguable.  Hubris is the first step to failure. Good leadership begins with humility.  I think it was  Tom Peters who noted many years ago,  “those that can’t lead..  are doomed to manage.”   Managers do things right..  leaders do the right things.   Managers are a type of leader..  but it’s the lowest rung on the ladder.

Leaders take almost none of the credit for success, but all of the blame for failure.  I use this simple truth to evaluate almost anyone on where they are as a leader, including myself.  Anyone  that I see blaming others for their shortcomings or failures, rates low in my estimation of them as a leader.  Conversely,  those that take blame, even when it isn’t due, rank high in my book.  When I find myself tempted to blame others for either personal or business problems..  (and it’s a common temptation)  there’s a check in my spirit.

There’s a great story in a military leadership book that I read years ago about a British military academy instructor who after telling his students about the leadership principles of a top military company was asked a question.  “Sir, what if you are assigned to command a lousy company?” The old warrior paused and said.. “son, if you have a lousy company, then you are a lousy commander.”

There’s actually something quite empowering about accepting full responsibility for a situation.   If I’m the problem..   then I’m the solution.  That leads to a lot more problem solving than wringing your hands over what someone else is doing.

Collins asked all of us two questions, that I’d like to ask each of you.

1. Are you proud of the professional choices you’ve made recently?
2. Are you proud of the personal choices you’ve made?

Great questions.

For more information on Jim Collins go to www.jimcollins.com