| 1.0 INTRODUCTION | | | | current (and will then present a very low |
| In this modern world, we have become very | | | | impedance path) between the "power-line" and |
| dependent upon our electronic gadgets. We use | | | | "electrical ground". |
| personal computers to work, communicate with | | | | At this point, all of this excessive energy (from |
| friends, family members or business associates. | | | | the electrical surge event) will be "routed" through |
| We often times store valuable files (such as | | | | the MOV devices (to electrical ground) and will be |
| financial documents, memos, reports, *.mp3 files, | | | | diverted away from your valuable electronics. |
| and now we also store important personal | | | | Once the "power-line voltage" returns to a normal |
| pictures) onto the Hard Drives of our Computers. | | | | level, the MOV devices will then return to their |
| We use the following electronic systems to | | | | "high-impedance" state and will cease to conduct |
| entertain, educate, enlighten and comfort us. | | | | current between the power-line and electrical |
| - DVD Players | | | | ground. |
| - HDTVs (e.g., LCD and Plasma) | | | | 3.2 SHOULD YOU USE SURGE PROTECTORS |
| - Video Recording Equipment (for those of you | | | | FOR EVERY ELECTRONIC SYSTEM/ELECTRICAL |
| upload your videos on to YouTube) | | | | APPLIANCE IN THE HOME? |
| - Gaming Systems (e.g., Nintendo, Wii, X-Box, etc.) | | | | In general, you should use surge protectors on all |
| - Central Air Conditioning System, Heat Pumps | | | | sensitive electronics that you would like to keep |
| - Microwave Ovens | | | | and use for some period of time. |
| These and other electronics gadgets require a | | | | If you have Surge Protectors for each of your |
| significant investment to obtain in the first place; | | | | sensitive electronics, then they will do a very |
| and are very expensive to repair and/or replace. | | | | good job protecting your electronics, for the |
| And yet, amazingly, we do very little to protect | | | | duration that they (the Surge Protectors) function. |
| our electronics from damage or attempt to make | | | | 3.3 WHAT ARE SOME THINGS THAT I SHOULD |
| them last (and serve us) longer. | | | | LOOK FOR WHEN SHOPPING AROUND FOR |
| This article is one of a series of three (3) articles | | | | SURGE PROTECTORS IN MY HOME? |
| that discusses how to protect your electronics | | | | In general, you should look for the following |
| against the following destructive mechanisms that | | | | parameters/metrics whenever you are shopping |
| shorten its operating life. | | | | around for Surge Protectors. |
| Heat | | | | Clamping/Let-Through Voltage |
| Electrical Surge/Spike Events, and | | | | Joules Rating |
| Electrical Noise | | | | Response Time (if available) |
| In this particular article, we are going to talk about | | | | I will explain each of these items below. |
| "Electrical Surge/Spike Events". | | | | 3.3.1 Clamping Voltage: |
| In particular, we are going to discuss the following | | | | The "Clamping Voltage" level is also (often times) |
| topics associated with "Electrical Surge/Spike | | | | referred to as the "Let-Through Voltage" level. |
| Events". | | | | Basically, this is the voltage level that will cause |
| What are Electrical Surge/Spike Events and How | | | | the MOVs (inside the Surge Protect system |
| are they generated? | | | | Power-Strip) to conduct electrical current between |
| How do you protect your electronics from | | | | the "power-line" and Electrical Ground. |
| Electrical Surge/Spike Events? | | | | At this voltage level, the Surge Protector will start |
| What are some guidelines that you should use | | | | to shunt the destructive electrical energy (from |
| when selecting a Surge Protector? | | | | an incoming surge event) to Electrical Ground and |
| 2.0 WHAT ARE ELECTRICAL SURGE/SPIKE | | | | will divert it away from your valuable electronics. |
| EVENTS? | | | | As I mentioned before, the MOVs will continue to |
| Electrical Surge/Spike events are typically defined | | | | shunt electrical current (from the power line) to |
| as a "large current/voltage transients that occurs | | | | Ground for the duration that the "Power-Line |
| in an electrical signal or the power-line". | | | | Voltage exceeds this "Clamping" or "Let-Through" |
| Surge events typically last for a few | | | | Voltage level. |
| microseconds and are then gone. Similarly, spike | | | | In general, the lower the "Clamping" or "Let |
| events will typically last for a few nanoseconds | | | | Through" Voltage level the better the protection |
| and are then gone. | | | | for your electronics. |
| NOTES:a. 1 microsecond = 1 millionth of a second, | | | | Typical values for "Clamping" or "Let Through" |
| andb. 1 nanosecond = 1 billionth of a second. | | | | voltage level are 330V, 400V, or 500V. |
| Both electrical surge and spike events can cause | | | | For 120V AC applications, I recommend that you |
| considerable damage to any electronic systems | | | | use a Surge Protector with a Clamping Voltage |
| that are electrically connected to these power-line | | | | level of 330V. |
| or signal-lines that are carrying this transient | | | | 3.3.2 The Joules Rating |
| current and voltage. | | | | The "Joules" Rating for a Surge Protector will |
| For a typical person that lives in a home and own | | | | typically define the cumulative amount of energy |
| some consumer electronics, electrical surge/spike | | | | that it (the Surge Protector) can absorb |
| events can fall into one of two categories. | | | | (throughout its operating life-time) without failing. |
| External Surge/Spike Events, and | | | | In general, the higher the number, the longer the |
| Internal Surge/Spike Events | | | | Surge Protector will last and continue to protect |
| I will briefly define each of these types of Surge | | | | your electronics. |
| Spike events below. | | | | Good Surge Protectors are ones that have a |
| 2.1 EXTERNAL ELECTRICAL SURGE/SPIKE | | | | "Joules Rating" of 1000J or better. |
| EVENTS | | | | NOTE: The "Joule" Rating does not reflect the |
| External Surge/Spike events are called "External" | | | | total amount of electrical energy that the Surge |
| because they occur "External" to (or outside of) | | | | Protector will shunt (to Electrical Ground) before |
| your home. | | | | failing. |
| External Surge/Spike events typically originate | | | | The "Joule" Rating reflects the amount of energy |
| from one of two sources. | | | | that the components (mostly the MOVs) within |
| Lightning Strikes (during an Electrical | | | | the Surge Protector can absorb without failing. |
| Thunderstorm), and | | | | In most cases, whenever an MOV shunts |
| Switching events within the Electrical Grid | | | | excessive voltage and current to ground (during a |
| External Surge/Spike events tend to be very | | | | Surge Event), it (the MOV) is only absorbing a |
| large and damaging (especially if they originate | | | | fraction of this energy. |
| from lightning strikes). | | | | Most of this energy is "being dumped" to Electrical |
| If these external surge/spike events were to | | | | Ground. |
| enter your home (via the main power line and | | | | If your Surge Protector is properly installed, then |
| through the circuit breaker panel), they will | | | | for every joule absorbed by the components |
| destroy pretty much any piece of electronics that | | | | (inside the Surge Protector) another 4 to 30 |
| is connected to an electrical outlet in your home. | | | | joules was harmlessly shunted from the |
| NOTE: These pieces of electronics do not need to | | | | Power-line to Electrical Ground. |
| be powered on to be destroyed. | | | | However, each time your Surge Protector |
| They only need to be plugged into an outlet in | | | | responds to a surge event, the MOV devices do |
| your home at the time when this catastrophic | | | | absorb some energy, and the cumulative amount |
| electrical surge/spike event occurs. | | | | of energy that these devices have absorbed |
| Fortunately, the External Electrical Surge/Spike | | | | moves closer and closer to the "Joules Rating" |
| events do not occur very often (e.g., a few times | | | | number and "failure". |
| a year depending upon what part of the world | | | | 3.3.3 Response Time |
| you live in). | | | | Surge Protectors do not respond immediately to |
| 2.2 INTERNAL ELECTRICAL SURGE/SPIKE | | | | Surge Events. |
| EVENTS | | | | There is a slight delay (or response time) before |
| Internal Surge/Spike Events (as the name implies) | | | | they respond. |
| are generated "internal" (or within your home). | | | | The longer this response time, the longer your |
| Internal Surges/Spike events typically occur | | | | electronics sits exposed to the incoming surge |
| whenever the motor or an appliance (such as an | | | | event. Fortunately, most surge events do not |
| Air Conditioner or the Refrigerator turns ON or | | | | happen immediately either. Most surge events |
| OFF). | | | | take several microseconds before they reach |
| Internal Surge/Spike events tend to be much | | | | their peak voltage. |
| smaller than External Surge/Spike events. | | | | By that time, most Surge Protection schemes |
| However, Internal Surge/Spike events occur | | | | (especially those using MOVs) will "kick in" within |
| much more often than do External Surge/Spike | | | | nanoseconds after the voltage level has exceeded |
| events (several times a day). | | | | the "Let Through" Voltage. |
| Over time, these smaller (though more frequent) | | | | 3.4 DO SURGE PROTECTORS LAST FOREVER? |
| internal surge/spike events will do damage to | | | | Just like the smell of a brand new car, Surge |
| your electronics as well. | | | | Protectors do not last forever. |
| Each time a motor of an appliance (such as an Air | | | | As these MOVs respond to Surge Events and |
| Conditioner or a Refrigerator) requires surge | | | | "shunt electrical energy to ground" over time, |
| current (for it to turn on), or anytime the | | | | they absorb some of that energy. |
| magnetic field (within the motor of an appliance | | | | This process causes "degradation" and "wear and |
| collapses) whenever it is turned OFF, a damaging | | | | tear" on the MOV devices (and in-turn) on the |
| surge or spike is generated and can propagate | | | | Surge Protectors as a whole. |
| throughout some of the power supply lines in | | | | Eventually these MOVs will fail in one of two |
| your home. | | | | ways.a. The MOVs will fail to the point that they |
| Internal surge events will shorten the operating life | | | | will no longer shunt excessive electrical energy to |
| of any electronic gadget that is plugged into an | | | | ground. In this case, the MOVs (are said to fail in |
| electrical outlet in your home. | | | | an "Open" state). |
| NOTE: The electronics gadget does not need to | | | | Whenever this occurs, all of your precious |
| be powered ON for it to sustain some damage | | | | electronics that is "downstream" from your Surge |
| from these internal surge/spike events. | | | | Protector are now "officially" un-protected and are |
| 3.0 HOW TO PROTECT YOUR ELECTRONICS | | | | now vulnerable to the next surge event that |
| FROM ELECTRICAL SURGE/SPIKE EVENTS | | | | comes around.b. At least one MOV device will fail |
| One of the most common ways of protecting | | | | into a "Short Circuited" Mode. In this case, the |
| many of your electronics from damage (due to | | | | MOVs may (though rarely) fail in the "Short |
| electrical surge/spike events) is through the use | | | | Circuit" state. |
| of "power strips" that contain "surge protection" | | | | Whenever this happens, the "failed" MOV device |
| circuitry within them. | | | | would continue to conduct high currents (from the |
| Many power strips have surge protection built in, | | | | Power-line to Electrical Ground) even when the |
| and in most cases, these types of power strips | | | | power-line voltage is less than the "Let Through" |
| are clearly marked to reflect this. | | | | voltage. |
| CAUTION: | | | | This type of failure mode could be very |
| There are some power strips that do not provide | | | | dangerous. |
| surge protection for your electronics. | | | | Fortunately, most Surge Protectors will typically |
| Often times, people will still (incorrectly) refer to | | | | have a fuse that will "blow" and will turn OFF the |
| these products as "surge protectors". | | | | Surge Protector entirely, rather than risk catching |
| If you are looking to purchase a Power strip that | | | | on fire. |
| contains "Surge Protection" circuitry, make sure | | | | The main message here is this. Internal Surge |
| that the labeling (on the box that you have in | | | | Events occur many times throughout the day. |
| your hands) clearly indicates "Surge protection" or | | | | As these events occur, and as your Surge |
| something like that. | | | | Protectors continue to function and shunt the |
| If you cannot quickly find those words on the | | | | excessive electrical energy to ground, these |
| box, then I recommend that you put that | | | | Surge Protectors eventually wear out and will |
| Power-Strip box back on the shelf and go find a | | | | need to be replaced. |
| Power-Strip that has "Surge Protection" clearly | | | | SOME GUIDELINES ON WHEN TO REPLACE |
| marked on it. | | | | SURGE PROTECTORS: |
| 3.1 HOW DO SURGE PROTECTORS WORK? | | | | You should replace your Surge Protectors under |
| Surge Protector circuitry typically works by | | | | the following conditions. |
| having devices (like an MOV - Metal Oxide | | | | 1. Whenever the Green "Protected" Light (on the |
| Varistor) that "sits" between the "power-line" path | | | | Surge Protector itself) goes OUT. |
| and electrical ground within the power strip. | | | | 2. If you've owned your Surge Protector for |
| Many Surge Protectors will have several of these | | | | more than 3 years. |
| MOV devices in order to make them more | | | | NOTE: Having the Green Light ON is encouraging |
| robust. | | | | but is not a guarantee of adequate protection for |
| Under normal operation, these MOV devices will | | | | the next surge events. |
| do nothing at all and do not affect the operation | | | | Replacing your Surge Protectors every three |
| of your appliances or electronic systems. | | | | years is a good practice to keep your electronics |
| For you electrical engineers out there, I will tell | | | | protected. |
| you that these MOV devices presents a very | | | | 4.0 OTHER ARTICLES IN THIS SERIES |
| high impedance between the "power-line" and | | | | In this article we have discussed one of the three |
| "electrical ground". | | | | main enemies of electronics and how they |
| If a surge event occurs such that the "power-line | | | | shorten the operating life of electronics and cost |
| voltage" exceeds a certain "threshold" voltage | | | | you money. |
| level, then the MOV devices will start to conduct | | | | Other articles in this series are listed below. |