The UK, like the rest of the world, generates and distributes AC power. AC is short for alternating current, and we use this because it’s easy to generate, switch and change the voltage. We use most of our power at low voltage but generate and distribute at high voltage because it’s more efficient to do so.

Alternating current means the supply voltage rises from zero to a maximum, drops back to zero and then does the same thing again in reverse. Conventionally we call the two ‘directions’ positive and negative. The mains supply here is 50 cycles a second and a cycle is one positive and one negative. The shape of the voltage rise and fall is sinusoidal so you can visualize one cycle as halt an ellipse going positive followed by one going negative.

Simplistically, think of a generator as a coil of wire rotating between two poles of a magnet.

The Power Quality Problem

Poor power quality costs money in lost production, services and nuisance tripping.

The Issue

Perfect power quality is achieved when the voltage is nominal (ie 230V +10% -6% in the UK) and the mains waveform is a perfect sinewave. There are no interruptions, voltage dips or momentary high voltages.

In practice, there are many factors that prevent this happening and these reduce power quality. Unfortunately, many of these are beyond the control of the electricity supplier.

There are rules and standards which define permissible variations in the mains power supply.

Problems and failures

Big changes in voltage and the shape of the mains waveform cause problems and failures such as:

  • Equipment failures
  • Unexplained trips and fuses blowing
  • Short equipment lives
  • Process failures and problems
  • Overheating cables and switchgear
  • Harmonics (current and voltage)

Business Costs 

When the cause of a problem, has been established, we can help you solve it. If the issues go unresolved they could effect your business;

  • Replacement equipment plus labour charges.
  • Production disruption.
  • Ramifications of failing to comply with applicable standards and rules.

Are you facing Power Quality issues. For a no obligation informal conversation, please contact us.

Contact Dale

How Dale Instruments can help

Dale Instruments can visit your site to discuss your power quality issues and then format an action plan.

Information Gathering

First of all, gather information. This involves talking to all employees affected to generate a history of what’s gone wrong and when, remedial action taken and results obtained.


Know your limitations. This demands a degree of honesty which can be unpalatable: your site maintenance staff can be good at sorting out run of the mill problems but your problem may be beyond their abilities. Don’t forget that the trouble and consequent costs continue until the problem’s solved.


Dale Instruments  have the  experience of understanding route cause of power quality issues and failures and so can provide a cost effective solution. Bear in mind that it may be necessary to become involved in an elimination process: sometimes a number of tests are needed to eliminate possible causes.

Establish a timescale

Ideally, you want to sort out the trouble immediately but you must accept that this isn’t usually possible: there are almost certainly site measurements required which may involve recording equipment and Dale Instruments  will want to know exactly what’s wrong  and how long the problem has existed.

Contact Dale Instruments for an informal discussion.

We can qualify from our discussion what the magnitude of the power quality problem is (if any)  and offer you competitive prices to carry out a power quality study on your site after analyzing the data, design and install hardware to mitigate power quality issues.

Our team has over 20 years experience and knowledge and good reputation for working with clients on solutions.

Timescale is important, Please note if your site or equipment is experiencing power quality failure then please contact us to work with you to eradicate the problem as power quality issues do not go away and in some case manifest into bigger problems and costs.

Dale Instruments Services can carry out competitively priced power quality studies and the involvement of the client is paramount at all stages of the survey and analysis.

Typical Examples of power quality failures on equipment.

  • Tripping of circuit breakers / Equipment operation. Possible causes are load unbalance, incorrect ratings or harmonic distortion.

  • Low lamp life. Possible supply voltage spikes or system high voltages. Site measurements for several days or weeks may be required

  • Inexplicable machinery stoppages. May be interference caused by other equipment or supply voltage dips

  • Machinery control malfunctions. May be due to power quality problems or harmonic distortion

  • Equipment failures may be caused by harmonics

  • Switch room equipment disastrous failures. Identified by major damage and often caused by voltage spikes including lightning strikes on the incoming supply.

Get in touch

Facing Power Quality issues? Provide your details, and we will contact you back.

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