Plant designation system AKZ

The plant designation system AKZ is a predecessor system for identifying plants, systems, sub-systems, and equipment items for plant operating companies. The implementation of AKZ is formalized by commonly known regulations. The AKZ system is now no longer developed and maintained as a designation system. The application is based on technology from 1975 and for this reason it is no longer recommended.

Identification of plants using this plant designation system comprised of a 9 to 10-character combination of letters and numbers. The letters were usually used for the classification of the systems and units, whereas the numbers were used for numbering.

The plant designation system AKZ distinguishes among 4 designation blocks:

Nummer der GliederungsstufenOrdnungsstufe 0Ordnungsstufe 1Ordnungsstufe 2Ordnungsstufe 3Ordnungsstufe 4
Aufbau des KennzeichensGesamtanlageSystemklassifizierungSystemzählungAggregatklassifizierungAggregatzählung
Aufbau der DatenstellenNAANNANNN

The plant designation system according to AKZ followed a fixed structure that was based on grouping levels for designation, whereby the level of detail of the designation increases from left to right. The structure of the grouping levels was alphanumeric. In the example we use A for letters and N for numbers for the sake of simplicity.

Designation block 0 of the AKZ system – Entire plant

The first designation block refers to the overall plant and merely numbers it. It only consists of one digit. This is used to identify the power plant unit.

Designation block 1 of the AKZ system – Function designation

The second of the four designation blocks denotes functions, systems, or subsystems of a power plant. This designation block consists of 2 letters. These were assigned according to a predetermined function key for the systems in power plants. The first letter (from the left) refers to the main systems (also known as the main groups); the following letters were used for further subdivision into subgroups. The AKZ function key for plant designation is defined but is no longer maintained centrally.

Example of a function key for AKZ

Electrical engineering

AHigh-voltage systems for power distribution, main transformer systems
AB110kV 162/3 Hz traction systems
AE110kV systems 50 Hz
AH50 kV systems
AJ20/25kV systems
AK10 kV systems
APGenerator leads
ATUnit transformers
AUCoupling transformers
AVUnit generator transformers
BHigh-voltage auxiliary systems and auxiliary transformers
BAHV unit auxiliary transformer, half busbar 1
BBHV unit auxiliary transformer, half busbar 2
BCMedium-voltage main system, starting system
BDMain distribution boards
BEMain distribution boards
BFMain distribution boards
BGMain distribution boards
BHUnit auxiliary generator and appurtenances
BJMain unit auxiliary system
BKUnit auxiliary batteries

Mechanical engineering

PFuel handling
PACoal unloading and storage
PBCoal treatment and transportation
PDOil unloading and storage
PEOil transportation and distribution
PGGas reception
PPWaste unloading and storage
PQWaste treatment
PWMeans of transportation for fuel
PYBrown coal dust transportation
QGas turbine systems
QATurbine and generator casing and rotor
QBTurbine bearing
QCOil system
QDCombustion chamber
QGExhaust gas, fresh air supply
QJStarting equipment
QKIgnition unit
QMOil firing
QNGas firing
QSCooling water system
QXStarting system
RWater-steam circuits
RAMain steam pipe, HP bypass
RBHot reheat pipe, LP bypass
RCCold reheat pipe
RD2. reheat
RE3. reheat
RFExtraction point for HP economizer
RGExtraction point for district heating
RHExtraction point for LP economizer
RJHeat transfer system

Designation block 2 of the AKZ system – Function numbering

Designation block 2 comprised of two characters. These were referred to as FN-numbering and were used for numbering.

Designation block 3 of the AKZ system – Equipment unit designation

The third designation block was used to label an equipment unit in the subgroup. It consisted of only one letter. The equipment units were classified according to a defined equipment unit key for power plants.

Equipment unit key for grouping level 3

AAnalyt. meas. (chem. analysis, pH value, conc. etc.)
BVessel, apparatus, heat exchanger
CClosed-loop control
DDriven machine, driving machine (pumps, blowers, …)
EElectr. meas. (current, voltage, frequency, etc. )
FFlow rate measurement, quantity measurement
HElectrical and I&C equipment (horns, revolving lights, etc.)
JPhotoelectric cells
KCharacteristic value calculation, protection equipment
LLevel measurement
MSpecial measurement (e.g. moisture, leakage, etc.)
NRoom, location, slot
PPressure (also differential pressure and tensile force)
QElectrical function symbol
RRadiation measurement
SValves, solenoid valves, limit sw., magnetic br.
TTemperature measurement
USignal processing from a control module, runtime sig.
VVibration, strain, length measurement
WElectrical steam tracing
XCurrently not assigned
YSpeed measurement
ZPiping element

Designation block 4 of the AKZ system- Equipment unit numbering

Designation block 4 comprised of 3 characters. The individual types of equipment units in each system of a count were represented by them.

Replacement with the KKS Identification System for Power Stations

The plant designation system AKZ was replaced by the KKS Identification System for Power Stations, because it did not provide a sufficient range for the designation system that was needed for the more modern power plants after 1976.

Existing power plants that still use the AKZ designation system have the one-time opportunity to convert to the KKS system or to extend their existing AKZ system with parts of the KKS Identification System.