Mains Supply Voltage Problems - Symptoms, Causes & Solutions

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Additional Advice & Guidance Resources

FREE Voltage Stabilisers Buyers Guide with advice and guidance on selecting the most appropriate AC Voltage Stabilizers and Regulators at cost efficient prices.

Voltage Stabilisers – A Buyers Guide to AC Voltage Stabilizers & Regulators

AC Automatic Voltage Stabilizers and Regulators - a Design Overview
Ashley Edison Global Power Protection Solutions
With our wide manufacturing base and the outstanding reliability of our electronic -servo and solid state stabiliser designs, our AC Automatic Voltage Stabilisers & Power Conditioners are on duty throughout the world - facing some of the most rigorous and demanding environments.
Every AC Voltage Stabiliser solution we offer is backed by the unrivalled experience we have gained in world markets over the last 25 years or so. In that time, our unique design innovations have set new performance levels and the breadth of our offering has broadened to accommodate the needs and ever demanding requirements of our growing Client base.
AC Automatic Voltage Stabilisers & Regulators
Electronic Servo             
SES Series
Single & Three Phase
1 to 500 kVA
SESL Series
Three Phase
150 to 2000 kVA
OSES Series
IP54 Outdoor
Single & Three Phase
6 to 500 kVA
SES-R Series
Rack Mount
Single Phase
3 to 10 kVA
Step Up / Down
Three Phase
10 to 100 kVA
AC Automatic Voltage Stabilisers & Regulators
Solid State       
PEN Series
Single & Three Phase
2 to 200 kVA
MVSI Series
Independent Phase Voltage Compensation
Three Phase
15 to 1000 kVA

Oil Cooled

IVSI Series
Independent Phase Voltage Compensation
Three Phase
500 to 2000 kVA
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AC Power Conditioners
PCV Series
Ferro Resonant
Single Phase
1 to 5 kVA
PCS Series
Servo Electronic
Single & Three Phase
1 to 150 kVA
PCEN Series
Solid State
Single & Three Phase
2 to 200 kVA
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  Voltage Sags Brownouts Over Voltages & Power Surges High Voltage Spikes     ● Electrical Noise Blackouts & Mains Failures Effects on Equipment

 Voltage Sags

Voltage Sag Power Problems



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Sags: are short duration decreases in the mains supply voltage which generally last for several cycles. 
Formal Definition – Voltage below 80 to 85% of rated RMS voltage for 2 or more cycles.
Typical symptoms - Sensitive equipment can lock or hang causing data loss and system resets.
Common Causes – Heavy equipment turned on, starting large electrical motors, switching of the mains supply.
Solutions -   AC Voltage StabiliserAC Power Conditioner &  Uninterruptible Power Supply.


Brownouts Power Problems


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Brownouts: are long term sags in the mains supply voltage which can last up to several days.
Formal Definition – A steady state of RMS voltage under nominal by a relatively constant percentage.
Typical Symptoms -Equipment can reset or even shutdown.
Common Causes – Heavy equipment turned on, starting large electrical motors, switching of the mains supply or just low voltage output from the generating source.
Solutions - AC Voltage StabiliserAC Power Conditioner & Uninterruptible Power Supply.

 Over Voltages & Power Surges

Over Voltage and Power Surge Problems


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Over-Voltage & Surges: are short duration increases in the mains supply voltage which generally last several cycles.
Formal Definition – Voltage above 110% of the rated voltage for 1 or more cycles.
Typical Symptoms - When surges occur equipment can suffer from premature failure. The high voltage causes wear and tear and general component degradation. This is often unnoticeable until failure occurs. Unusual heat output can be an early sign of problems ahead.
Common Causes – Heavy equipment being turned off.
Solutions - AC Voltage StabiliserAC Power Conditioner & Uninterruptible Power Supply.

 High Voltage Spikes

High Voltage Spike Power Problems



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High Voltage Spikes: these are very fast high energy surges or spikes in voltage lasting only a few milliseconds.
Formal Definition – Rapid Voltage peak up to 6,000 volts with a duration of 100msec to ½ a cycle.
Typical Symptoms - Equipment can lock or hang, crash and even suffer damage which inevitably causes data loss and corruption.
Common Causes - Switching of equipment, especially heavy inductive loads, arcing faults or atmospheric electrical disturbance, such as lightning strikes and static discharges.
Solutions - AC Voltage StabiliserAC Power Conditioner, Isolation Transformer, Uninterruptible Power Supply.

 Electrical Noise

Electrical Noise Power Problems



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Electrical Noise: this is a high frequency noise either common or normal mode.
Formal Definition – Electrical noise is high-frequency interference on the incoming mains supply.
Typical Symptoms - Processing errors, computer lock-up, burned circuit boards, degradation of electrical insulation and equipment damage.
Common Causes – Electric motors, relays, motor control devices, broadcast transmission and microwave radiation.
Solutions -  Isolation Transformer, AC Power Conditioner & Online Uninterruptible Power Supply

 Blackouts & Mains Failure

Blackouts and Mains Failure Power Problems





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Blackout and Mains Failures: when the mains supply fails completely this is known as a total mains failure or blackout.
Formal Definition – Loss of incoming mains supply
Typical Symptoms - Complete disruption of equipment operation. A break in the mains supply of only several milliseconds is sufficient enough to crash, lock or reset many of the components that make up a typical data or voice processing IP network, such as PC, terminal, console, server, PBX, printer, modem, hub or router.
Common Causes - Storms, lightning, wind and utility equipment failure. Typically occurs as a result of  loss of power, a mechanical failure, or overloading by consumers.
Solutions - Uninterruptible Power Supply &  Diesel Generator

Effects of supply voltage variations on different types of equipment


Voltage Reductions Effects

Voltage Increases Effects
Computers An 8% drop will often cause computer errors and downtime. A 10% rise will cause computer damage, errors and downtime.
Lighting A 10% voltage drop reduces lumen output by over 25% (15% for florescent tubes). Infra Red lamp heat output is reduced by over 20% A 10% volt rise reduces life expectancy of incandescent lamps by over 50%.
Radio & TV Transmission Volt drop will reduce quality of the transmission and coverage range. Over voltage by 2% will significantly reduce tube life.
Photographic Processing A 5% volt drop will increase exposure times by 30% and reduce quality of colour printing significantly. Voltage rise during printing cycles will cause inferior results
X-Ray Equipment A 1 % change in the filament voltage of an X-Ray tube will produce an 8% change in the anode current. When used at its maximum rating an X-Ray tube will be permanently damaged in the case of a 5% volt rise.
Magnetic Equipment A 10% volt drop can cause relays / contactors to open chatter. Solenoids become sluggish and vibration will cause malfunctions and overheating. Over voltage will cause magnetic core saturation high current and overheating. Wear and distortion is increased.
Induction Heating Heat output is reduced by more than 20% on a 10% volt drop. Heat output varies approximately with the square of voltage.
Welding Equipment A 10% volt drop will increase a welding cycle by 20% if weld quality is to be maintained. A 10% volt rise will overheat a weld, reducing quality and causing possible “burn through”.
Transformers At 100 kVA a 10% drop will reduce transformer rating to 90%. A 10% rise will considerably increase core losses and decrease efficiency proportionally.
AC Motors A 10% volt drop reduces torque by approximately 18%. Motor life expectancy is reduced due to overheating. A 10% volt rise causes higher starting current and reduces power factor by approximately 5%.

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