Tuesday, March 30, 2010

HOW TO PROTECT YOUR ELECTRONICS FROM ELECTRICAL SURGE EVENTS

1.0 INTRODUCTION
Here in the 21st Century, many households (across the U.S. and much of the developed world) have acquired and now use many cool electronics gadgets, that includes the following.

PC (either Desktop or Laptop)
DVD Players (some of these are portable and can be taken anywhere you go as you travel).
Video Recording Equipment (for those of you that like to post videos on youtube or on your blog or website)
Gaming Systems (such as the Playstation variants, Nintendo, X-Box 360, Wii, etc).
High Definition TVs (which contains more features and greater resolution than could ever be imagined in the past)
And More.

We have come to depend on these electronic gadgets and appliances to enlighten, educate, entertain, comfort us and make our lives more convenient.

If we were to just look at the PC and what all we do with that hunk of electronic gear;
We communicate with friends and family or business associates (certainly through email, Social Networking sites, transmission of video through the various "IM/Chat" medium)
We conduct financial transactions (we purchase products, we sell products, etc.)
We download, or write and store important documents (either for personal purposes or for business purposes)
We download and store music (in the form of *.mp3 files)
We store photos and images that we have captured from our Digital Still Cameras (which would be very difficult to replace if lost).

The point is that we have become very dependent upon your electronics.

Many of these products required a considerable investment to obtain in the first place.

Additionally, if would cost us even more to replace or repair these products.

Yet, for the amount of money that we invest in these products, it is amazing to me that we invest such little effort or money into protecting our electronics systems from damage, or in trying to extend the operating life time of these systems.

In this article we are going to discuss the following topics.

What are Electrical Surge/Spike events and how are they generated?

How do we protect our electronics from damage due to electrical surge/spike events?

What are some guidelines that we should follow in selecting Surge Protectors?

When should you replace your Surge Protectors?

2.0 WHAT ARE ELECTRICAL SURGE/SPIKE EVENTS?
Electrical Surge/Spike events are a prominent member of the "destructive horsemen" that will either destroy your electronics or reduce their operating life-time.

The other two prominent members of the this "electronics destruction team" are

Heat, and

Electrical Noise

An electrical surge/spike event is defined as a transient voltage/current condition that occurs in (either the signal path or the power lines) such that the current and voltage levels greatly exceed the "normal range" for a short duration (typically from a few nanoseconds to microseconds).

During this "transient period" excess electrical energy is being "dumped" onto your electronics.

This excess electrical energy can inflict a lot of damage to your electronics.

Electrical Surge/Spike events typically fall into two categories.

External Electrical Surge/Spike events, and

Internal Electrical Surge/Spike events.

I will discuss each of these types of Electrical Surge/Spike events below.

2.1 WHAT ARE EXTERNAL ELECTRICAL SURGE/SPIKE EVENTS?
External Electrical Surge/Spike events are called "External" because they originate external to (or outside of) your home.

External Electrical Surge/Spike events are typically caused by:
Lightning Strikes (e.g., from a thunderstorm, etc.) or
Switching Events within the Electrical Grid

External Electrical Surge/Spike events tend to be much larger and more powerful than that of its "Internal" counterpart.

Fortunately, the External Electrical Surge/Spike events occur MUCH less frequently than do the "Internal Electrical Surge/Spike events".

Most parts of the world will experience a few to about 40 lightning strikes each year.

If a lightning strike does occur near your home, and if a large portion of the energy (from the lightning strike) were to traveling along the main power line and into your home (through the Circuit Breaker panel); then virtually every piece of electronics that is plugged into an electrical outlet (within your home) will be destroyed and destined for "eWaste Heaven".

NOTE: An electrical system does not need to be powered ON for it to be destroyed by this surge event.

It only needs to be plugged into an electrical outlet at the time the surge event occurred - then "boom" the power supply circuitry (in your electronic system) is "smoked".

2.2 WHAT ARE INTERNAL ELECTRICAL SURGE/SPIKE EVENTS?
Internal Electrical Surge/Spike events are called "Internal" because they originate internal to (or inside) your home.

Internal Electrical Surge/Spike Events are typically caused by electrical appliances in your home (say, the Refrigerator or the Central Air Conditioning Motor) turning ON and turning OFF.

An Internal Electrical Surge/Spike event will occur whenever that surge of current occurs (to turn on the Central Air conditioning Motor).

Likewise, an Internal Electrical Surge/Spike Event will also occur whenever the Central Air Conditioning motor is turned OFF and the Magnetic Field (within the motor) collapses.

Internal Electrical Surge/Spike events are not near as severe as that of its "External" counterpart.

However, Internal Electrical Surge/Spike events occur far more often than do the "External" variants.

Internal Electrical Surge/Spike events will occur in your home several times each day.

Internal Electrical Surge/Spike events will not suddenly "blow out" your electronics (like the External Electrical Surge/Spike events will).

Internal Electrical Surge/Spike events will (over time) "chip away" at your electronics and will greatly shorten their lives.

3.0 HOW TO PROTECT YOUR ELECTRONICS FROM ELECTRICAL SURGE/SPIKE EVENTS
The best way to protect your electronics from damage due to Surge/Spike events is to use Surge Protectors.

Surge Protectors come in a variety of shapes and forms.

However, Surge Protectors are most commonly sold in the form of "power-strips".


3.1 HOW DO SURGE PROTECTORS WORK?
In general, there are two types of Surge Protectors out on the Market.

There are "Shunting" Surge Protectors and, and
There are "Blocking" Surge Protectors

I will describe how each of these types of Surge Protectors work below.

3.1.1 HOW DO "SHUNTING" SURGE PROTECTORS WORK?
Most of the Surge Protectors that you can buy (for consumer electronics/small office applications) are of the "shunting" type.

Most "shunting" type of Surge Protectors contain MOV (Metal Oxide Varistor) devices.

Many Surge Protectors will contain multiple MOV devices in the effort to make them more robust.

During normal operation (whenever there is no surge event), the power-line voltage will be below a "Threshold Voltage" level (which is known as the "Clamping" or "Let-Through" voltage).

In this condition, the MOV devices (within the Surge Protector) will present a very high-impedance between the Power-Line and electrical ground and will not conduct any current between the power-line and electrical ground.

In this case, the MOV devices (and the Surge Protector as a whole) will not affect the operation of the "protected" electronic system downstream.

The MOV devices will simply "sit" between the power-line and electrical ground and continuously monitor the power-line voltage.

Now, if a Surge Event were to occur, and if the power-line voltage were to now exceed the "Clamping voltage" level, then the MOV devices (within the Surge Protector) will start to present a "low-impedance" path between the power-line and electrical ground, and will proceed to conduct current between the power-line and electric ground.

At this point, the MOV devices will proceed to protect your electronics by "shunting" all of this excessive electrical energy to electrical Ground, and diverting it away from your "protected" electronics.

The MOV devices will continue to operating in the "low-impedance/current-conducting" state for the duration that the power-line voltage is greater than the "Clamping Voltage".

Once the power-line voltage drops below the "Clamping Voltage", then the MOV devices will stop conducting current and will return to the "high-impedance" condition.

At this point, the Surge Protector will now permit normal electrical power to flow to your "downstream" electronics.

3.1.2 HOW DO "BLOCKING" SURGE PROTECTORS WORK?
During normal operation (whenever there is no surge event), the Surge Protector circuitry will allow the power-line voltage and current to be transmitted over to the "protected" electronics, as is.

However, whenever a surge event occurs, and whenever the "power-line" voltage exceeds the "Clamping Voltage", then the "Blocking-type" of Surge Protector circuitry will cease to transmit the power-line voltage and current to the "protected" electronics.

In this case, the "power-line" voltage and current are "disconnected" from the "protected" electronics.

The "protected" electronics will not receive any current or voltage from the power-line for the duration that this condition exists.

Once the surge event has subsided, and the power-line voltage drops below the "Clamping Voltage", then the Surge Protector will resume the transmission of power-line current and voltage to the "protected" electronics.

3.2 GUIDELINES FOR SELECTING SURGE PROTECTORS
Whenever you are out shopping for Surge Protectors, there are various things that you need to keep in mind.

Surge Protectors come in numerous different forms, but a very common form (that they come in) are in the form of "power strips".

Many people believe that all "Power-strips" are Surge Protectors.

In fact, there are some people that simply refer to "power-strips" as "surge protectors".

This is not true. While many Surge Protectors are also "power-strips"; not all "power-strips" are "Surge Protectors".

If you are at an electronics or office supply store and if you pick up a box that contains a power-strip, check the label/markings on the box to see if you can find the words "Surge Protector" or "Surge Protection".

These words should appear very prominently on this box.

If you cannot find these words on the box, then I recommend that you place this box back on the shelf and go find another box that does contain those words on its labeling.

Additionally, whenever you are out shopping for Surge Protectors, you should be mindful of the following parameters/metrics for Surge Protectors.

Clamping Voltage,

The Joules Rating, and

Response Time

I will define each of these parameters below.


3.2.1 CLAMPING VOLTAGE
The "Clamping Voltage" level is often-times referred to as the "Let-Through Voltage" level.

This is the "Threshold Voltage" for the MOV devices within the Surge Protectors.

Pleases see Section 3.1.1 for information on how the MOV devices will function whenever the power-line voltage is "above" and "below" the "Clamping" Voltage.

In general, lower "clamping voltage" levels offer better protection for your electronics.

You can typically find Surge Protectors with "clamping voltage" levels of 330V, 400V and 500V.

For most 120V AC Applications, I would recommend that you use Surge Protectors with a "Clamping voltage" level of 330V.

3.2.2 JOULES RATING
The Joules Rating reflects the total (or cumulative) amount of energy that the Surge Protector can absorb during its operating life-time before failing.

Each time the Surge Protector detects and responds to a surge event (by shunting electrical power to electrical ground), it absorbs some of the electrical energy that it is handling (as it shunt all of this electrical power to ground).

Each of these surge events "takes a toll" on the MOV devices within the Surge Protector, and will eventually cause these devices (and the Surge Protector as a whole) to fail.

In selecting your Surge Protector, the higher the "Joules rating" the better. The higher Joules rating means greater protection and a longer lasting Surge Protector.

I would recommend that you get a Surge Protector that has "Joules rating" of 1000J or better.

Whenever these MOV devices (within the Surge Protector) fail, they can fail into one of two modes.

Where the MOV devices no longer shunt electrical power to ground, and

Where the MOV devices are stuck in the short-circuited condition

I will discuss each of these failure conditions below.

WHERE THE MOV DEVICES NO LONGER SHUNT ELECTRICAL POWER TO GROUND
If the MOV devices fail into this mode, then they will no longer switch into the "low-impedance/current-conducting" mode whenever the power-line voltage exceeds the "clamping voltage" level.

In this case, the MOV devices are no longer protecting your "electronics" downstream.

When there is a surge event, your electronics are now going to receive the full-brunt of this incoming surge event.

What makes things worse is that you most likely do not even know that this old Surge Protector is useless, and that your electronics are completely vulnerable.

This is not a good deal for your electronics or your bank-account.


WHERE THE MOV DEVICES ARE STUCK IN THE SHORT-CIRCUITED CONDITION
If the MOV devices were to fail into the "short-circuited" mode, then they would continue to operate in the "low-impedance/current-conducting" state, even when the power-line voltage is below the "Clamping Voltage" level.

This particular failure mode does not happen very often. Most of the time, if this failure mode were to occur, it would be in the aftermath of a very large, catastrophic (external) surge event.

If one or more of these MOV devices (within the Surge Protector) were to fail into this short-circuit condition, then a large amount of current will flow between the power-line and electrical ground for an indefinite period of time.

This could be a very dangerous condition and could result in a fire.

Fortunately, most Surge Protectors contain a fuse, which would "blow" under these high-current conditions and will simply "kill" the Surge Protector altogether.

In this case, the Surge Protector would no longer transmit the power-line voltage and current to the "protected" electronics and would need to be replaced.


3.2.3 RESPONSE TIME
Surge Protectors do not immediately respond to the on-set of Surge Events.

There will be some delay, between the on-set of a Surge event and the instant that the Surge Protector invokes protection (by shunting current to ground).

This delay time is known as the "Response Time".

In general, a shorter "Response Time" usually means better protection for your electronics.

During this "Response Time" your "electronics" are just "sitting there" fully exposed to the incoming Surge Event.

Fortunately, most surge events require a few microseconds for it to reach its peak voltage (NOTE: 1 microsecond = 1 millionth of a second).

Once the power-line voltage exceeds the "Clamping Voltage" level then the MOV devices (within the Surge Protector) will respond to this condition within nanoseconds and invoke protection (NOTE: 1 nanosecond = 1 billionth of a second).

Therefore, in most cases, your "Surge Protector" should invoke protection long before the electrical surge event reaches its peak voltage.

3.3 WHEN SHOULD YOU REPLACE YOUR SURGE PROTECTOR?
In general, you should replace your Surge Protector whenever any of the following are true.

If the "GREEN" or "PROTECTED" light (on the Surge Protector) has gone out, or

If you have been using a Surge Protector for about 3 years (even if the "GREEN" or "PROTECTED" light is still illuminated).

As Surge Protectors sustain more and more surge events, the cumulative amount of energy that they absorb will creep closer and closer to that "Joules Rating" number. Often times, you will not know how close your Surge Protector is to its Joules ratings number or to failure.

The "GREEN" or "PROTECTED" lights being on are not a certain indicator that you have sufficient protection for your electronics.

The cost of replacing your Surge Protectors is typically far less than that of replacing your computer or HDTV system.



4.0 OTHER ARTICLES IN THIS SERIES
This article is part of a series of three (3) articles on mechanisms that either outright destroy or reduce the operating life-times of your electronics.

Other articles in this series are listed below.


How to Protect Your Electronics from Electrical Noise


5.0 CONCLUSIONS
In this article, we have discussed the following items.

What are Electrical Surge/Spike events and how are they caused?

What can we do to protect our electronics from damage due to these surge/spike events?

As we discussed Electrical Surge/Spike Events, we concluded the following.

That surge events occur very frequently (Internal Electrical Surge/Spike events - that is).

That you should use Surge Protectors on pretty much any electronic system that you would like to keep for a long time.

That you should make sure and not just pick up and purchase Power-Strips, because not all Power Strips have Surge Protection circuitry within them.

That you should also have other parameters (such as Clamping Voltage, Joules Rating and Response Time) in mind when shopping for Surge Protectors, and

Finally, that you should replace you Surge Protectors every three years or whenever the "GREEN" or the "PROTECTED" lights (on the Surge Protectors) go OUT, which ever come first.



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