Surge Protection

So sorry, the ful specification is

Surge Protection Specs: PHoenix Contact (VAL-MS BE Order No.: 2817741)

OK, now the full spec. search worked. Looks like you need to call the mfg. applications engineers. I must say, I can't understand the purpose of the fuse...

Most surge protectors just turn black when the"ve had enough.

NYOJ

The fuse or circuit breaker are for protection from one of the common failure modes of MOV-based surge arrestors : once the cop a decent surge they can fail short-circuit.

It shouldn't make much diffierence if the protection is a fuse or a CB, but the manufacturer's recommendation is the trump here.

Some brands of surge arrestor have an internal fuse which mostly eliminates this issue.

The essential answer: what the customer wants, is not necessarily what the customer needs.

VAL MS has an internal feature of THERMAL DISCONNECT, which electrically isolates the plug after its service life, and ensures NO SHORT CIRCUIT during failure, atleast I am yet to come across one.

Having done that kind of engineering:

1.) fuses and CBs ARE NOT SURGE ARRESTORS.

2.) fuses and CBs are NOT the same thing and are NOT interchangeable. They do different things. A 100 amp breaker will pass MUCH more current than a 100 amp fuse. I once tested a 30 A automotive breaker, it tripped at 100A in about 3 seconds.

3.) Client has what reason for "wanting that?" CLient will get really tired of replacing fuses that blow when there is no fault.

Fuses and CBs limit LOAD CURRENT. They are in SERIES.

Suppressors limit TRANSIENT VOLTAGE and are in PARALLEL to ground.

Lacking even this basic knowledge, you should not be working on this system.

@Benotype, For sure, it is possible to replace fuse by circuit breaker to protect a Surge Protection Device (SPD). Those short circuit protective devices(SCPD) must be coordinated with the SPD upstream. To know which exact type of circuit breaker do you need, it is necessary to know the characterist of VAL-MS cartridge (because your reference is the base element alone)If the SPD cartridge is Imax=40kA(8/20) MCB type could be C curve 16A but this information has to be confirmed by the manufacturer
For more information, I let you read the "Wiki EIG" chapter "Protection against voltage surge in Low Voltage" with the link below:
http://www.electrical-installation.org/enwiki/Detailed_characteristics_of_the_external_SCPD

Thank you all for your immense contribution. Thank you obouill for the link you added to your thread. it was very,very,very rich. Thanks

Thank you very much for your contribution. I'm almost done with the job but have a littlle question to ask you. In a three phase and nuetral connection, will it be possible to use varistors and gas discharge tubes surge protection device rated at nominal 230V and arrested rated volatge of 275V? Or probably a rated nominal voltage of 400V and arrested volatge 0f 440V.

From my research i have only seen nominal voltage 400V MOV used in three phase supply without nuetral. I just want to be sure.Thank youvery much

http://www.electrical-installation.org/enwiki/The_components_of_a_SPD

The link you included in this reply shows three voltage limiting varistors in line with each of three phases, tied together on one line and then in series with the gas discharge tube. It would need to be close to your point of connection (power hookup) to be effective. Every 12 inches of leadwire between the devices and the power connection de-rates the overvoltage protection by about 500 volts peak.

Perhaps what you were looking to understand is that the gas discharge tube becomes conductive at some given voltage and acts very much like a switch. That also means that its impedance changes from very high to very low in a matter of microseconds. The Varistors (voltage limiting devices) retain a substantial amount of resistance but it decreases rapidly beyond a certain threshold. That absorbs some of the energy in the surge but it can only handle some percentage of the surge. The more (in parallel) the better.

You also need to remember that in any AC power system, your stated voltage is the RMS value. For a single phase peak voltage, you must multiply the RMS value by the square root of two or 1.414. In a three phase system, you can treat the phase to neutral loads as single phase but for a phase to phase connection (or device) it requires an RMS multiplier of the square root of 3 or 1.732 for the normal peak voltage. Consequently, as shown in the example in your link, the varistors for your 230 Vrms system would be rated at 400 volts and the gas discharge tube would be rated at a fairly low (limit above normal) voltage (say 40V?).

Lastly, you need to remember that these components don't last forever, especially if they have to work very hard. You can put several varistors in parallel in order to survive longer. When they quit working, they usually fail in a high resistance (nearly or actually open circuit) mode. If you find the right kind, they will change color when they reach end of life.

You may expecting to build a surge supressor at some savings to yourself. This will not be the case unless you buy in quantities of several thousand components at a time. If this is a one time effort, you will spend less by just buying a standard surge supressor from some manufacturer that purchases his components that way. And he will know how to put them together to really get the benefits.

Engineering isn't about giving Clients what they want. It's about giving them what they can have.