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Power Quality is becoming more important as electrical equipments are increasingly used in the industrial plant. Besides being sensitive to short voltage fluctuation, this equipment also produce harmonic which can degrade the power quality in the power system. Incompatibility between power supply and the industrial equipment can cause mal-operation of customer equipment or degradation in the quality of industrial product. Monetary losses due to power quality problem can be as high as outage problem.

How does it affect you

Loads or customer's equipment determine the appropriate level of power quality. Different equipment requires different level of power quality.

Power Quality problem is "Any problem manifested in voltage, current or frequency deviations that result in the failure or misoperation of any electrical equipment and installation". It can originate internally from customer own electrical system and externally from utility power system or other customers within the vicinity or due to natural causes.

Major power quality problems are related to voltage dips (or voltage sag), transients and harmonics.

Addressing equipment operational compatibility

The customer is responsible to ensure that its equipment will perform its function duly in an electrical environment. This can be achieved via taking step to ensure all the power quality parameters (or Electromagnetic Compatibility) are incorporated in the equipment specification and design. On the other hand, the utility is responsible in ensuring acceptable level of reliability and manage power quality in the electrical environment so that it will not be degraded.

How to request for higher level of Power Quality

The request for higher level of Power Quality should be forwarded during initial supply application as it will be incorporated into the overall power system design. The extra cost of providing such higher level of power quality shall be borne by the customer.

How to handle Power Quality issues

Power Quality problem occurs in every power system around the world. International standard bodies e.g. IEEE (US), EEE (UK) and IEC (Europe) are producing documents on power quality guidelines and standards as reference to the power utilities, equipment manufacturers and equipment users.

The best way to avoid power quality problem is by ensuring all equipments to be installed are compatible with power quality in the power system. This can be achieved by procuring equipment with proper technical specifications that incorporate power quality performance of its operating electrical environment. Background power quality survey should be done in order to obtain better information on the existing power quality parameters.

Recommended steps to troubleshoot Power Quality issues

Step 1:
Record the dates & times of the disturbance.Take voltage measurement (if necessary, for suspected under/overvoltage cases).

Step 2:
Check when the problem normally occurs i.e. at certain times of a day or at random.

Step 3:
Identify components that are frequently affected.

Step 4:
Refer to TNB for data correlation to identify the types/sources/causes of the disturbances.Provide voltage measurement (if available).

Step 5(a):
If the types/sources/causes are unknown, install power quality monitoring equipment. Diagnose the new data recorded.

Step 5(b):
If the types/sources/causes originated from TNB’s system, TNB will implement mitigation measures to minimize the occurrence of the same problem again. Some of the problems may mitigated by rearranging the supply reticulation or by improving its protection philosophy.

Step 6:
If the types/sources/causes are known, discuss with equipment manufacturers for minimizing the emission of the disturbances or improve the immunity of the equipment.

Step 7:
Implement mitigation measures.

Related Documents

• TNB Power Quality Handbook - Voltage Sag Solutions for Industrial Customers

To learn more, click here for Power Quality FAQs