Power quality-energy-saving-fluke

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Fluke Europe BV Eric van Riet 1

Fluke Power Quality and Energy Savings

Welcome


Questions to ask…

• Does a better quality of the power grid or power system automatically lead to energy saving?

• Is energy efficiency the same as energy saving (i.e. cost saving)?

• Is investing in energy efficient motors and lighting the road to a trouble free power grid?

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The primary playground for PQ and energy saving:

• What consumes the energy in the Power Grid?

– Loads

– Losses in system

• What creates the current Power Quality issue’s we face?

– LOADS


• Current situation:

– Standard 3-f motor, 70% mechanical load, direct connection

To save energy:

• Use energy efficiënt motors.

• Use ASD’s

• Size properly!

• Reduce load

• Perform regular maintenance

• Turn it off

Example with electrical motor

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Another option: ASD in combination with motor to “tune” motor to load

Energy loss in a

pump system when

a throttling valve

controls flow

Energy loss in a pump

system when an

adjustable speed drive

controls flow

Source: US Dep of Energy


Energy consumption using an ASD

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Effects of long cabling

• ASD Output • Motor Terminals


• Source of EMC problems

• Disastrous for isolation of motor windings

Overvoltage

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Flow of harmonic Currents


Bearing Current

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Current in PE conductor


Power Quality and cost saving

• Where are the costs in the Power Grid?

– Energy bill (amount of € per KWh…..or)

* Connection value (size of conductor)

– Estimated lifetime power system (aging due to use)

* System loading

* Connected components/loads

• Cost saving in energy most likely marginal with same mechanical load.

• Hidden cost saving present, but…..

• Also higher chance on PQ problems leading to higher cost

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What about lighting

• Lighting is also a large consumer of energy

• Latest trend pushing strongly for energy efficient lighting like:

– T5 and comparable fluorescent lighting

– Electronic ballasts versus conventional ballasts

–LED Lighting


Voltage and Current

Traditional lamp 60W Ledlamp 6W

27 Arms 18 Arms

Measured current is equivalent of 100 lamps

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Real Power comparison

Normal lamp 60W Ledlamp 6W

59 Watt/lamp 6.4 Watt/lamp

Ledlamp 10 x less dissipated power(W)


Cos phi


No difference in Cos phi

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Apparent Power


60 VA/lamp 41 VA/lamp

Apparent Power ledlamp 32% less


Harmonics

Test object :Led Lamp

Mains voltage with voltage THD of 8% (limit of EN 50160)

Harmonics far above limits IEC 61000-3-2 (2005) class D

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Transformer losses

• Transformer losses are proportional to frequency of the harmonic current times the amplitude of that harmonic.

• When a non-linear load is supplied from a transformer, it is sometimes necessary to de-rate the transformer capacity to avoid overheating

• The de-rating of a transformer is

expressed by the k-factor


Measured k-factor

Normal lamp Led lamp

The measured K-factor of the LED lamp is more that 400 !!!!

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Measured k-factor

Lighting is consuming 17% of the total electric energy. If all traditional lighting is replaced by LED then :

- Total Real Power will decrease 10-15%

- Total Apparent Power will decrease with 5-7%

- The total K-factor of the grid will increase with a factor 5-10

This means that the total installed base of transformers needs to be extended/replaced multiple times.


Answers to the questions…




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PQ issues vary by location, so also the

measurement needs vary by location

No system is alike, hence no “solution” will

have the same effect on different systems

Real impact only visible through proper

measurements!!

Measure to see the impact






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Food for thought

• Investing and engineering in order to save energy is a good thing.

• Blindly applying “energy saving solutions” is NOT a good thing.

• You can only improve a system or situation if you really know what is going on….

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So MEASURE!

Quote Lord Kelvin (1824 – 1907):

–To measure is to know

– If you cannot measure it, you cannot improve it

Thank you

Education

Power quality-energy-saving-fluke