What information belongs on a nameplate?
Nameplate or rating plate is an inherent part of each drive system component, such as the transformer, variable frequency drive (VFD), electric motor etc. Therefore, it makes sense to spend few paragraphs on the topic. This post explains the content of information on a nameplate.
What is a rating plate?
Rating plate (nameplate) is a plate or a combination of several plates affixed to the equipment in a way that they can be easily read when the equipment is in a normal position. The rating plate states the rating of the equipment plus some additional information. International standards, such as IEC or IEEE, mostly specify the minimum information that the rating plate shall indicate. The manufacturer of the equipment can extend the information on the nameplate beyond the minimum requirements of the applicable standard.
Minimum information on a nameplate
As mentioned, the minimum information to be stated on a nameplate is defined in corresponding standards.
For transformers those standards are
For VFDs the requirements regarding rating plate are defined in
Finally for motors the respective standards are
Let’s have a look at each drive system component separately.
Transformer nameplate
The nameplate of a transformer shall contain following information:
– Rated power
– Rated voltages and insulation level
– Rated ambient temperature
– Cooling class
– Transformer type
– Number of phases
– Impedance value (measured)
– Rated frequency
– Connection diagram
– Vector diagram (winding connection)
– Tapping voltages and tap connections (if applicable)
– Unit weights
– Conductor type
– Protection type
– Rated temperature rise
– Serial number / Identification number
– Third party certification (if applicable, e.g. UL)
– Manufacturer name
The overall amount of information depends among others on the complexity of transformer. Special multi-winding connection, tertiary winding(s), wide range of taps etc shall be mentioned on the nameplate as well. For complex transformer designs it is quite common to have multiple plates in order to indicate all the relevant information.
Besides the rating plate, transformers may additionally be equipped with a diagram plate. Such plate shows the winding connection, information about tap changer, information about mounted instruments etc. Example of rating and diagram plate of a large liquid-immersed transformer is shown below.
VFD nameplate
Rating plate of a VFD shall state following information:
– Identification number an serial number
– Manufacturer’ type designation
– Rated input voltage, current and frequency
– Number of output phases
– Rated output voltage, current and frequency
– Range of output voltage
– Range of output frequency
– Type of duty
– Max. permissible short circuit current
— Reference to design standard (IEC 60146 in this case)
Example of a VFD rating plate is depicted in figure 3 (ABB’s ACS6000 medium voltage drive).
Motor nameplate
The information belonging to motor nameplate is defined in IEC 60034. Below we list the items applicable for AC machines:
– Serial number and identification number
– Manufacturer’s machine code
– Number of phases
– Degree of protection (IP class)
– Efficiency class (IE code) if applicable
– Thermal class and temperature limits
– Type of duty
– Rated output or range of rated output
– Rated voltage or range of rated voltage
– Rated frequency or range of rated frequency
– Rated current of range of rated current
– Rated speed or range of rated speed
– Permissible overspeed
– Rated power factor
– Details about excitation system (for synchronous machines only)
– Maximum coolant temeprature
– Minimum ambient temperature
– Design altitude (if above 1’000 m.a.sl.)
– Total mass (approximate)
– Direction of rotation
– Reference to design standard
For VFD fed medium voltage motors following information shall be stated in addition to normal rating plate:
– Rated torque
– Torque at minimum speed
– Lowest speed at rated torque
– Minimum / base / maximum speed
The content of this post is intended to provide basic orientation. For detailed information refer to applicable standards or other literature on the subject. Consider subscribing to our premium subscription for in-depth information on topics around medium voltage variable frequency drives (MV VFD) and drive systems.
References
[1] IEC 60146-1-1: Semiconductor converters – General requirements and line commutated converters – Part 1-1: Specification and basic requirements
[2] IEC 61800-4: Adjustable speed electrical power drive systems – Part 4: General requirements – Rating specifications for a.c. power drive systems above 1 000 V a.c. and not exceeding 35 kV
[3] IEC 60034-1: Rotating electrical machines – Part 1: Rating and performance
