z
geie
g
r
h
a el
rd r
the guru
60
Be dedicated,
experience
will come with
time.
Paris, France-2000: Sachdev, Ziegler
and Sidhu
CIGRE Paris 2002: Gerhard Ziegler
with Graeme Topham
"Have you ever
considered
leaving
protection?"
No, never.
PAC.SPRING.2009
CIGRE Honorary Member
System
protection
offers
interesting
challenges
and career
possibilities.
I think that
experienced “old hands” and
young ambitious engineers can
build a strong team.
Biography
Gerhard Ziegler was born in
1939, and has been working
in the area of power system
protection with Siemens
AG in Erlangen/Nuremberg,
Germany for a period of 35
years.
He was active on a world-wide
basis in the areas of product
support, application and
project planning, marketing
and sales. He retired in 2002,
but continues to work as a
consultant.
G. Ziegler has published
numerous national and
international contributions
in the area of power system
protection.
He served for many years in
International organizations.
From 1993 to 2001 he was
the German delegate to the
IEC TC95 (measuring relays
and protection equipment). He
is past chairman of the Study
Committee 34 (protection and
local control) and Honorary
Member of CIGRE. .
PAC.SPRING.2009
62
I like reading.
I still read a lot,
PAC World: Can you tell us something about where you were born including technical
and where you grew-up?
G.Z: I was born 1939 in Berlin. books.
But during the war our house was
bombed and we went back to the
rural Franconia near Nuremberg where both my parents are
from. So I am not a real Berliner. I grew up in the after war
time in a then small village where the roads were not paved
and water had to be fetched at a fountain in the yard.
These were simple circumstances which we however
shared with many other people at the time. I had a lucky
nature-liking childhood which I wouldn’t want to replace.
PAC World: Is there something special in your childhood that affected your future career?
G.Z: There is no crucial experience, as far as I can remember.
I am not very talented at arts like music or painting and I was
always more interested in technical things. My grandfathers
had a carpenter and a blacksmith business. It was great fun
passing the time in their workshops. Later in school, I got
the best marks for the scientific subjects. The choice of an
engineering carrier was therefore obvious.
PAC.SPRING.2009
PAC World: Do you have any engineers in your
family that made you think about following in their
footsteps?
G.Z: My father was an engineer and served as a demolition
expert in the army. He died after the war in an accident when
a dud aerial bomb exploded during the defusing work. He is
the only engineer in our family as far as I know.
PAC World: Did you have any special interests while in
school?
G.Z: My main interest, besides school, was dedicated to
sports, in particular soccer. The wide array of free time
activities offered nowadays did not exist at the time.
PAC World: How did you decide to study electrical
engineering?
G.Z: The technical direction was predetermined by my
single sided talents and interests in this field. In high school,
I was occupied with space technology and Wernher von
Braun was an example for me. (One of the fathers of space
technology, Herman Obert, lived in a neighboring village).
The more humble goal to become a traditional electrical
engineer is probably based on the fact that SIEMENS, at the
time, had its main seat, a large research center and a number
Gerhard Ziegler
of factories in the region (Erlangen/Nuremberg). SIEMENS,
an active world-wide company, offered a variety of attractive
jobs with a life time secure income and pension.
PAC World: Where did you study? Did you study protection while in the university?
G.Z: I studied at the technical University in Munich with
emphasis on power engineering, at the time called “Heavy
Current Technique”. The relaying subject was not really
treated. We got only some information about the basic
protection principles, and a demonstration panel with some
black box relays existed.
PAC World: Did you have any other interests while
studying in the university?
G.Z: I think, besides sports, there is no other activity worth
mentioning. My aim was to pass the university time as
fast as possible and to get a job because my mother as a
widow could not give me much financial support. I had to
concentrate on the studies to pass tests to get the state grant
for needy students.
PAC World: Where and how did you start your career?
G.Z: Right after the university, I joined SIEMENS in a
trainee program which allowed me to work three years in
three different areas. I began with the calculation of electrical
machines, worked then in the test field for large generators
and finished the trainee program with the development of
thyristor based motor control. This time was very interesting
because I could work at innovative projects: computer based
motor design and simulation, water cooling of generators
and the application of thyristors - all new at the time.
PAC World: What made you change your focus on
power system protection?
G.Z: This was not intentional. At the end of my trainee
program I wanted to go back to the SIEMENS motor factory
in Nuremberg, because it was located not far from my home
and I wanted to work in the field of electrical machines.
There was no suitable position for me at this time, so the
head of the trainee department recommended that I work in
the protection department. This department had a machine
protection group and I could occupy myself there with my
favorite subject until a suitable position would be found.
This was my first contact with protective relaying and the
start of a 35 year career in this field. I declined a later offer
from the motor factory which I never regretted.
PAC World: You spent your whole career with a single
company? What was your role during the different
stages of your career?
G.Z: Spending the whole work life in one company was
quite normal in Germany for people of my generation. The
positions were normally filled by people from within the
company and you could make a career without job hopping.
I started as project engineer in the machine protection group.
I think, about three years later I changed to the network
protection group. I was then responsible for sales support and
project management in part of Germany and Central/South
America. In 1978, I became the leader of a newly organized
technical protection department. Our tasks included product
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63
specification, control of development and application
support. This was the most stressful part of my career. We
had extended our business to overseas markets considerably
and had to handle a large number of big projects.
The new numerical relay range which was launched in 1985
was a great success, but needed a lot of technical support
in the start-up phase until sufficient experience had been
gained with this new technology. In this phase, I was also
heavily engaged in information and training of users about
the new numerical relay technology.
In 1990, I took over the task of marketing, consulting and
strategic planning with a smaller group of experts. I travelled
a lot world-wide during this time, wrote many papers and
was present at numerous conferences. Further, I was active in
the IEC and CIGRE. In 2002, I retired after a very interesting
career in protective relaying which lasted for 35 years and
covered the three stages of electro-mechanical, solid-state
and numerical technology.
PAC World: How do you compare the transition from
electromechanical to solid-state relays with the transition to microprocessor based relays?
G.Z: The transition from electromechanical to solid-state
relays took a longer time. Some utilities even did not accept
this technology and went directly to digital relays.
The reason is probably that there was no price advantage and
the technical progress was not so obvious, in particular for
simple relays in the distribution range. Solid state relays also
had some drawbacks - the aging of components (capacitors)
causes a drift of the operating characteristics which makes
PAC.SPRING.2009
Gerhard Ziegler
the guru
64
The biggest
challenge
I faced was the
recalibration necessary. The digital
technology convinced the users from transition to
the beginning as there are obvious
economical and technical advantages. international
Think of the many integrated
functions, like fault recording in the standards
multi-function relays. One feeder,
one relay is now the standard in distribution. Further,
maintenance is considerably reduced due to self-monitoring
and the possible remote communication.
PAC World: Did you see any major differences in the
protection philosophy of utilities around the world?
G.Z: SIEMENS has a world-wide relaying business and
I had contacts with utilities in most countries. You can
indeed observe different philosophies. Basically you have
the Central European (IEC) and the English (IEE) or US
(ANSI/IEEE) influenced regions. Think of the themes low/
high impedance differential protection, definite/inverse
time relays, Quadrilateral/Mho characteristics, switched/
non-switched distance relays or blocking/permissive
teleprotection schemes. Other differences are based on the
grid conditions and the types of switchgear.
You have countries with long lines where the system
stability is critical and redundant teleprotection, power
swing blocking and local back-up protection is crucial. In
industrialized countries with heavily meshed networks,
stability is normally not a problem and second zone
tripping of line end faults may be acceptable. Thus a single
teleprotection scheme with a distance back-up protection
may be acceptable. Auto-reclosing practice has of course also
PAC.SPRING.2009
had some influence on the relaying practice.
PAC World: What do you think about the use of two
identical relays as Main 1 and Main 2 protection on an
important transmission line?
G.Z: There are some utilities who accept this policy. There is
however some risk of common mode failures. Most utilities
also do not rely on only one vendor. I think, the policy of
using different relay types or dissimilar protection principles
(distance and differential) will be maintained also with digital
relays. The now available relays with differential and distance
protection in one unit may then be an acceptable solution
when the total system is to be supplied by one vendor.
PAC World: We have seen significant improvements in
the functionality of distance protection relays. Do you
think that there is something more that can be done?
G.Z: I think the measuring technique has matured to a
reliable state. Newer relay generations may go to higher
sampling rates, calculation speed and storage capacity, but I
do not expect a significant improvement in the protection
performance. The function integration may however
proceed. There are now line relays on the market which have
full scheme differential and distance protection integrated in
one relay. It is further possible to use the distance relay as bay
unit for busbar differential protection.
However, I think it is more important that the operation and
setting of relays is further improved to make the setting of
the many parameters more user friendly and to avoid hidden
setting failures.
PAC World: Most of the relays today are based
on sequence components that work properly for
Making a wish turning the ring of the 'Beautiful fountain'
transposed lines. Do you think it is time to use relays
working in the phase domain on untransposed lines?
G.Z: This was considered in the past, in particular for the
fault locator function. The many more parameters would
however make the relay setting and testing much more
complicated. Considering that the error caused by the
non-transposition is only in the range of 5 to 7 %, the phase
domain solution seems not to be justified. The correction of
the fault locator result could be made off-line.
PAC World: When and how did you get involved in
CIGRE activities?
G.Z: I started as a working group member in the 1970's.
The first group I took part in was on “Coordination of
solid-state relays and conventional instrument transformers”.
The convener was Michel Chamia, the later chairman of
CIGRE. I learned a lot about the transient behavior of CTs
and CVTs from the experts Korponay (BBC) and Gertsch
(Micafil). I remember well the final discussion of the WG
report at the CIGRE, SC34 Colloquium in Melbourne, 1979,
where the US delegates had to defend their 5A CT standard
against the 1A practice of the rest of the world.
PAC World: What do you think is the importance of being involved in CIGRE working groups?
G.Z: The advantages are manifold. You learn about the
practice in other countries and you can share the knowledge
with experts for utilities and manufacturers. The personal
contacts with experts are helpful beyond the WG activity
and also are valid for the concerned companies. For young
engineers it is a chance to improve their language and
communication skills.
PAC.SPRING.2009
Gerhard Ziegler
PAC World: How did you share your knowledge and
experience? Did you write papers or books, or did you
directly teach your younger colleagues?
G.Z: I wrote many papers and delivered contributions to
conferences world-wide. I have also published two books:
“Numerical Distance protection” and “Numerical Differential
Protection”. I am further active as a lecturer at the Siemens
Power Academy in Nuremberg. I have always been in contact
with young people in our company or at universities. I like
it. They have learned from my relaying and power system
experience and I have benefitted from their better knowledge
about modern digital processing and communication. I think
that experienced “old hands” and young ambitious engineers
can build a strong team.
PAC World: Do you still participate in conferences? Do
you still present papers?
G.Z: I participated in conferences worldwide. I was less
engaged in the IEEE work as this was always handled
by local SIEMENS people. During my CIGRE SC34
chairmanship I was several times invited as key note speaker.
I still contribute as coauthor to papers, but I no longer visit
conferences or write papers myself. I think it’s time to leave
that stage to the young people.
PAC World: What do you think about the changes in
technology that we use for protection today and when
you started?
G.Z: When I joined the relaying department of SIEMENS in
1968, electromechanical relays were still the current practice.
The solid-state technology was at its beginnings. The new
solid-state relays were designed as open racks for cubicle
mounting with draw-out modules, which was causing a lot
of work. The wiring and testing in the workshops was time
consuming, and the interference and high voltage testing
were always critical. The setting of the electromechanical
and solid-state relays was comparably simple as only a few
plugs and bridges had to be positioned. The commissioning
however was time consuming as many meters had to be
connected and the finding of wiring errors was difficult.
The situation has now completely changed with the digital
technology. The drawing and wiring work has been widely
replaced by system configuration and parameterization at the
PC. Relay setting is done menu-guide with a relay operating
program at the laptop. The commissioning is simplified
because all voltage and currents are measured and indicated
by the relay itself. The connection of external meters is no
more necessary. Fault analysis is now also much easier by
evaluation of the fault record with powerful programs.
PAC World: What do you think of the impact of IEC
61850 on the future of protection?
G.Z: So far the impact on protection only concerned the
communication interfaces. A more dramatic impact would
mean the introduction of the process bus as the measurement
functions would be directly concerned and the transmission
of sampled measuring data on the bus is very complex. I am
no longer involved in detail in this theme so that I cannot
give any reliable comment.
the guru
65
Making a wish:
The “Beautiful
fountain" is
located in the
main marketplace
of Nuremberg,
where people can
make a wish to
come true.
Gerhard Ziegler
turned the ring
three times,
360 degrees,
wishing success
for all people in
protection.
Gerhard Ziegler
the guru
66
Gerhard Ziegler with his wife Hermine at their
house in Schwarzenbruck, Germany
PAC World: What was the biggest challenge that you
faced as a protection engineer?
G.Z: I think the biggest challenge I faced was the transfer of
the SIEMENS relay range from the originally German based
standard to a world-wide accepted international standard.
I engaged myself in the product specification, testing,
application and marketing. Of course many other people in
the development, manufacturing and sales side cooperated.
The relays were originally designed in close cooperation with
the German utilities. I think we were quite successful and
the full turn around to a global player was achieved with the
digital relay generations.
PAC World: What is your definition of retirement?
G.Z: A new life section with more time for my family,
hobbies, and traveling.
PAC World: What do you like to do when you are not
working?
G.Z: I have a large garden and two grandsons who keep me
busy. Reading and traveling to foreign countries is planned.
PAC World: What books do you like to read?
G.Z: Historical books, travel reports and still technical
literature.
PAC World: Do you have a favorite food?
G.Z: I have to watch my weight. Therefore I prefer fish.
Unfortunately I have a sweet tooth which I often cannot
withstand.
PAC World: You have travelled a lot. Do you have a
favorite place to visit?
G.Z: The favorite place for me and my wife is Paris. Due to
my CIGRE activities we were there every 2 years.
PAC World: What music do you usually listen to?
G.Z: I like to listen to classical music, but I am also a fan of
traditional country music.
PAC.SPRING.2009
Skiing is one of the
things that I really enjoy doing
PAC World: What do you think we need to do as an
industry to attract more young people to our field?
G.Z: One good opportunity is the cooperation with
universities to inform about protection and engage the
students early on in their studies in basic development
projects. The companies must assist universities and provide
facilities (sample relays, test set, study orders, etc.) so that
system protection can be included in the curriculum.
PAC World: What do you think about the young engineers in electric power systems protection?
G.Z: Many of the young engineers I know are very ambitious
and dedicated to the subject, and have very good theoretical
basis. Experience will come in time. So I have no doubts that
we will have good successors.
PAC World: Do you have a motto?
G.Z: Don’t take yourself too seriously!
PAC World: Is there something that you like to tell the
students that you teach?
G.Z: System protection offers interesting challenges and
career possibilities for young engineers. The protection
engineer is faced on one hand with the power system and its
dynamic/transient behavior and on the other hand with the
modern digital processing and communication technology
of modern relaying schemes.
PAC World: Is there anything that we missed?
G.Z: Yes: “Have you ever considered leaving protection?”
No, never.