ELEVATOR COORDINATION.

B

binwork91

Senior Member
Location
new york
Occupation
electrical engineer
See the one line below.

The 75A elevator fuse coordinates with the 150A XT4N breaker and the 1200A A4BQ fuse. However, the 150A XT4N and the 500A XT5N breakers do not coordinate with the 1200A A4BQ fuse.

Does this comply with 620.62?

Based on the code language, it appears to comply. However, if a fault occurs on the load side of the 500A XT5N breaker, both elevators may lose power.

My question is: Do the 150A and 500A breakers need to coordinate with the upstream 1200A fuse?

620.62 Selective Coordination​


Where more than one driving machine disconnecting means is supplied by a single feeder, the overcurrent protective devices in each disconnecting means shall be selectively coordinated with any other supply side overcurrent protective devices.
Selective coordination shall be selected by a licensed professional engineer or other qualified person engaged primarily in the design, installation, or maintenance of electrical systems. The selection shall be documented and made available to those authorized to design, install, inspect, maintain, and operate the system.
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The 500A breaker is not part of the supply to the elevator so it does not need to be considered when determining coordination.
 
Why is your fuse going to trip before the breaker? That sounds odd.

Or do you want the fuses to trip before the elevator breaker?

In theory you want the 75A fuses to trip before the 150A breaker so that only one elevator is tripped if a fault occurred load side of the fuse. If the breaker trips before the fuse than you are uncoordinated and takes out both elevators.
 
Elect117 said:
Why is your fuse going to trip before the breaker? That sounds odd.

Or do you want the fuses to trip before the elevator breaker?

In theory you want the 75A fuses to trip before the 150A breaker so that only one elevator is tripped if a fault occurred load side of the fuse. If the breaker trips before the fuse than you are uncoordinated and takes out both elevators.
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Yes, a 75A fuse coordinates with a 150A breaker.

The 150A and 500A breakers do not coordinate with the upstream 1200A fuse in the instantaneous trip region.
 
Your 75A elevator fuse coordinates with the 150A XT4N breaker, but are they selectively coordinated? Did you check the manufacturers tables to see that they are selectively coordinated down to 0 seconds?
 
ron said:
Your 75A elevator fuse coordinates with the 150A XT4N breaker, but are they selectively coordinated? Did you check the manufacturers tables to see that they are selectively coordinated down to 0 seconds?
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yes, They are coordinated down to 0 second. Per TCC create by Easypower
 
I don't see a problem with it. It says "the OCP in each disconnecting means shall coordinate...."

It doesn't seem to say anything about coordination between the upstream devices.

binwork91 said:
Instantaneous region overlap.
Click to expand...

Are you ignoring everything above the available fault current?
 
ron said:
I believe the EasyPower TCC only goes down to 0.01 seconds. The manufacturer's table is needed to get to 0 seconds.
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That is good to know. Question: is there a big different between 0.01 sec and 0 sec? I see most TCC only down to 0.01 sec.
 
Below 0.1sec you do not know how the device works. The curve may drop straight down or it might take a turn to the right. The only thing you can do is test the devices in series and see which clears first.
I think GE used to publish down to .001sec, but they were the only one that did.
 
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In EasyPower, you can display down to 0.001, but as Jim said, most TCC provided by manufacturers stop at 0.01. If EasyPower has data down to 0.001 in its library, it will display the curve if you zoom out. Some fuse curves go to 0.001. If a current-limiting fuse is in its current-limiting range, the fault will be cleared before 0.01 sec. Years ago, Cutler Hammer redid all of their MCCB curves to go down to 0.001.

Here's a Siemens MCCB curve that goes down to 0.001.

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