The Zap of Lightning

A ThunderBolt Zapped near our Home. The Power Shut down, The Earth Leakage Circuit Breaker ELCB tripped.

The Problem was a Mains Strip Board, It was the Puncture and Short of Y-Caps. Power strip - Wikipedia, the free encyclopedia

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The caps that were used are very good caps 630V DC rated, but not approved Y-Caps. And five other similar boards have survived, The Board that was zapped is 12 Years Old. It was the same board that had given some problem in the Kitchen a year back.

The cap at the left, who Broke Down saved other equipments, saved my day. The lightning bolt was so loud, it woke me up, in sound sleep. I am sure even a Good Y-Cap would have failed, The Bolt from the Blue was a Big one.

This reminds me of a friend of mine who used to Troubleshoot equipment by Sniffing. I saw him sniff out with his nose, Shorted Tantalum Caps in A Genrad Danbridge. Genrad means General Radio, And the LCR bridge was Huge made of discretes and Simple ICs.

More on Genrad

• ietlabs.com-Genrad
• quadtech.com
• teradyne.com

One thing leads to another, the Celestial Spark has ignited old Memories. The Chain Reaction Reminds me of another being who could identify Metals by Tasting-Sniffing. He would detect Platinum and Gold, wires and Plating in Old Valves and Antique Telecom Equipment.

Good Earthing Prevents Shocks

Good Earthing Prevents Shocks and Prolongs Appliance Life

Earthing in the olden days was done like this, i have just mixed what i have heard with my common sense and this is what it may be.

Make a deep pit, 4 feet deep, 1/2 feet dia, put long copper rods ( GI pipes or lead pipes were also used). Let the copper rods be driven deeper than the four feet that has been dug. mesh the rods with copper mesh or wire (GI chicken mesh). Fill the pit with all the conductive things which are bio-degradable, non-toxic, non-corrosive and non-soluble. They used coal, charcoal, salt, scrap metals. (now they have a polymer conductive gel). Terminate the copper rods to a thick copper wire run it to your mains box in a way it cannot be cut or broken when gardening etc.

The mains box should be fitted with HRC fuses and MCBs as required, use a ELCB too. The MCB trips when a over current load is drawn, there are both thermal (thermostat technology) and electromagnetic (relay technology) MCBs. The ELCB does not have a earth wire, it trips when the current in the live and neutral paths are unequal. When the difference is say 20mA it trips. This 20mA would have gone thru the ground wire or thru a person giving shock. Also use Over Voltage and Under Voltage Trips if possible, Many equipment fail due to this.

HRC -- High Rupture Capacity.
MCB -- Miniature Circuit Breaker.
ELCB -- Earth Leakage Circuit Breaker.
GI -- Galvanized Iron

Also do not forget a lightning rod on the top of the house, whose path to ground is far from the earth pit. Lightning also zaps phones etc. Use Zener barriers for all interfaces between equipment and isolation transformers.

Cable TV wires, phone wires, and mains wires all may get mixed up. During rainy days even a phone line or TV cable may give shock or blow input circuits in equipment. This may be due to mains leakage or lightning.

Before you touch any metal object, cross your fingers, better still buy a long neon tester.

Additional Study

• Earthing system
• Earthing Your Hi-Fi - Tricks and Techniques
• Design of Earth Electrode Systems
  

UPS Background

Standards

CBEMA - Computer Business Equipment Manufacturer's Association
adopted curve IEEE Standard 446 (orange book) curve.

Recommended Practice for Emergency and Standby power systems for Industrial and Commercial Application."

• Wave form Sine wave THD (total harmonic distortion) maximum 5%.
• 3 Phase system phase imbalance of voltage 3% - 6%.
• Frequency stability 60 (50 Hz in India) +/- 0.5Hz.
• Output Voltage +6% Max. -13% Min. from Nominal Value.
• Voltage can fall to 0V but should recover in 0.5 Cycles.
• On turn on Voltage should reach steady state within two seconds.
• Upto 200% over Nominal Voltage should be tolerated for 100uS. ( Transients, spikes and Inductive Kickbacks come in this)
• Upto 30% over Nominal Voltage should be tolerated for 0.5S.

ANSI - American National Standards Institute

"Standard Voltage Ratings for Electrical power systems & Equipment"

• Steady State Variations +/- 5% of Nominal Voltage. T
• Three Phase Voltage Imbalance 5% Max..
• Standard Frequency 60Hz.

Glossary

• Frequency 60Hz Hz is Hertz.
• One Cycle = 20mS (milliseconds) one full sine wave.
• In India Standard Frequency is 50Hz.
• Max - Maximum
• Min - Minimum
• uS - micro seconds, S - seconds.

Cause of Transients

1. Switching Loads Simultaneously (inductive loads).
2. Power factor correction capacitors and devices.
3. Lightning strikes (enhanced by earth faults).
4. Line Inductance (inductive kickback, resonance).
5. DC and AC Drives for Motors.
6. Rectifiers with large filters and stray inductance.

Extra Reading

• Power Standards Lab
• CBEMA Guideline
• ITI (CBEMA) Curve PDF

UPS Inverter

• Power Inverters DC-AC
• Keep your networking gear going 24/7
• Various Schematics and Diagrams
• A Mos-Fet Power Inverter
• Circuit makes simple high-voltage inverter
• Electronic Transformer - Inverter Transformer
• 500 WATT DC-AC by SM0VPO
• 12 Volt DC to 120 Volt AC Inverter
• 110VAC Inverter for Automobile
• A High-Powered Power Backup Inverter
• DC to AC Circuits and Inverter Circuits
• Power electronics - choppers, inverters, motor drives