EPO switch power

[jap]

They have been installed in these areas for years.

JAP>

 

[jap]

Even some larger mobile generators have shunt trip Mains in them so if you open the access door while its running it trips the main out.


JAP>

 

[ron]

In ALL other repects the contactor set up is more reliable and fail safe.

I guess it depends on your definition of more reliable .....

Although I haven't had to put an EPO in a data center in years due to code language; when I was, I put it in but made it easy for a failure to result in power remaining on!

I would never have used a normally open contactor, so I was sure in a failure condition, the data center blinking lights ..... didn't stop blinking

 

[iwire]

I am on my smart phone, I will get back to this later.

 

[jim dungar]

Basically shunt trips are used as they are the cheapest way to get it done.

Personally I think they are unreliable due to the reasons already mentioned.

Like gadfly I think normally open contactors are a much better way to go. They self supervise themselves and the control circuit.

If cost was the only concern, 'undervoltage trip' coils are certainly more in line with shunt trips than are separate contactors.
If 'shunt trips' are so inherently unreliable, why do Medium Voltage breakers depend on them?

 

[iwire]

If cost was the only concern, 'undervoltage trip' coils are certainly more in line with shunt trips than are separate contactors.
If 'shunt trips' are so inherently unreliable, why do Medium Voltage breakers depend on them?

Jim, those MV instaltions have supervised battery backed up control circuits.

If the systems jap and I are talking about had those control systems I would not be saying that they are unreliable.

As far as costs I see it time and time again shunts are a cheaper instaltion than contractors for more reasons than the cost of the shunt

 

[jap]

Jim, those MV instaltions have supervised battery backed up control circuits.

If the systems jap and I are talking about had those control systems I would not be saying that they are unreliable.

As far as costs I see it time and time again shunts are a cheaper instaltion than contractors for more reasons than the cost of the shunt

We were talking about the reliability of shunt trip versus contactor not the reliability of the control power.



JAP>

 

[iwire]

We were talking about the reliability of shunt trip versus contactor not the reliability of the control power.



JAP>

No I have been speaking of the system, if you look at my posts you will see I said shunts and contractors are equal as far as mechanical reliability.

 

[jap]

No I have been speaking of the system, if you look at my posts you will see I said shunts and contractors are equal as far as mechanical reliability.

Your very crafty with your wording then.


JAP>

 

[jim dungar]

Jim, those MV instaltions have supervised battery backed up control circuits.

If the systems jap and I are talking about had those control systems I would not be saying that they are unreliable.

As far as costs I see it time and time again shunts are a cheaper instaltion than contractors for more reasons than the cost of the shunt

I have been in many, and even designed several, installations where the trip voltage is not monitored.
In fact there was one mill I was in where the battery bank output was being monitored, but every one of the branch breakers, had been turned off so there was no way to operate any MV breaker.

We regularly add a Capacitor Trip device or even a small UPS in order to have reliable shunt trip AC power for a couple of hundred dollars.

 

[iwire]

OK I give up

I still install shunt systems but will never be convinced they are as reliable without control circuit supervison.

 

[cppoly]

I also would like to add after thinking about it that it takes micro seconds for electricity to travel whereas breaker shunt trips take what 1/2 to a second? This can be 1,000 times faster. So now I feel better.

 

[jap]

OK I give up

I still install shunt systems but will never be convinced they are as reliable without control circuit supervison.

I will agree with you that electrically operated devices are not very reliable if the electricity is not available to operate it.

JAP>

 

[jap]

I also would like to add after thinking about it that it takes micro seconds for electricity to travel whereas breaker shunt trips take what 1/2 to a second? This can be 1,000 times faster. So now I feel better.

Keep it simple.
Hook it up and hit the button.
If it don't work try something different.

JAP>