Initial Power Draw After Power Outage
 

We had a power outage last night. It was in the mid-80's and I'm sure
that most of us had our AC units just sitting there waiting to spin up
as soon as the power came back on - I know I did.

So how is that initial power requirement handled by the power
company?

Even in a relatively small outage like we had, the initial demand as
everybody's AC units, cable boxes, lights, pool filters, fans, fridges
& freezers, etc. all come on at the exact same moment must be huge.

How does the power company soften the impact on their equipment?

Initial Power Draw After Power Outage
 

On 7/11/2011 1:55 PM, DerbyDad03 wrote:
We had a power outage last night. It was in the mid-80's and I'm sure
that most of us had our AC units just sitting there waiting to spin up
as soon as the power came back on - I know I did.

So how is that initial power requirement handled by the power
company?

Even in a relatively small outage like we had, the initial demand as
everybody's AC units, cable boxes, lights, pool filters, fans, fridges
& freezers, etc. all come on at the exact same moment must be huge.

How does the power company soften the impact on their equipment?

Generally first by staging the return of any larger sections then that's
what "spinning reserve" is for for the makeup.

There will be some voltage sag and short term redistribution within the
local grid as well.

--

Initial Power Draw After Power Outage
 

On Jul 11, 5:21*pm, dpb wrote:
On 7/11/2011 1:55 PM, DerbyDad03 wrote:

We had a power outage last night. It was in the mid-80's and I'm sure
that most of us had our AC units just sitting there waiting to spin up
as soon as the power came back on - I know I did.

So how is that initial power requirement handled by the power
company?

Even in a relatively small outage like we had, the initial demand as
everybody's AC units, cable boxes, lights, pool filters, fans, fridges
& *freezers, etc. all come on at the exact same moment must be huge.

How does the power company soften the impact on their equipment?

Generally first by staging the return of any larger sections then that's
what "spinning reserve" is for for the makeup.

There will be some voltage sag and short term redistribution within the
local grid as well.

--

plus most ACs have a high current limit switch that opens for a moment
when overloaded like trying to start after a outage

Initial Power Draw After Power Outage
 

On Mon, 11 Jul 2011 14:47:50 -0700 (PDT), bob haller
wrote:

On Jul 11, 5:21*pm, dpb wrote:
On 7/11/2011 1:55 PM, DerbyDad03 wrote:

We had a power outage last night. It was in the mid-80's and I'm sure
that most of us had our AC units just sitting there waiting to spin up
as soon as the power came back on - I know I did.

So how is that initial power requirement handled by the power
company?

Even in a relatively small outage like we had, the initial demand as
everybody's AC units, cable boxes, lights, pool filters, fans, fridges
& *freezers, etc. all come on at the exact same moment must be huge.

How does the power company soften the impact on their equipment?

Generally first by staging the return of any larger sections then that's
what "spinning reserve" is for for the makeup.

There will be some voltage sag and short term redistribution within the
local grid as well.

--

plus most ACs have a high current limit switch that opens for a moment
when overloaded like trying to start after a outage


Most AC and refrigeration equipment have a delay that usefully takes
up to 5 min or more after power is interrupted, allowing the pressure
in the compressor to equalize. If the pressure is not equalized it is
likely that the compressor will try and start, but instead draw a
large current and trip whatever high current device there is in the
system. It is not desirable not to use the high current limiting
device as it can shorting the life of the compressor.

Initial Power Draw After Power Outage
 

On Jul 12, 10:26*am, wrote:
On Mon, 11 Jul 2011 14:47:50 -0700 (PDT), bob haller
wrote:





On Jul 11, 5:21*pm, dpb wrote:
On 7/11/2011 1:55 PM, DerbyDad03 wrote:

We had a power outage last night. It was in the mid-80's and I'm sure
that most of us had our AC units just sitting there waiting to spin up
as soon as the power came back on - I know I did.

So how is that initial power requirement handled by the power
company?

Even in a relatively small outage like we had, the initial demand as
everybody's AC units, cable boxes, lights, pool filters, fans, fridges
& *freezers, etc. all come on at the exact same moment must be huge.

How does the power company soften the impact on their equipment?

Generally first by staging the return of any larger sections then that's
what "spinning reserve" is for for the makeup.

There will be some voltage sag and short term redistribution within the
local grid as well.

--

plus most ACs have a high current limit switch that opens for a moment
when overloaded like trying to start after a outage

Most AC and refrigeration equipment have a delay that usefully takes
up to 5 min or more after power is interrupted, allowing the pressure
in the compressor to equalize. If the pressure is not equalized it is
likely that the compressor will try and start, but instead draw a
large current and trip whatever high current device there is in the
system. It is not desirable not to use the high current limiting
device as it can shorting the life of the compressor.- Hide quoted text -

- Show quoted text -

I believe he is refering to a longer delay without power. In which
case the compressor will try to start immediately.

Initial Power Draw After Power Outage
 

On 7/11/2011 4:21 PM, dpb wrote:
On 7/11/2011 1:55 PM, DerbyDad03 wrote:
We had a power outage last night. It was in the mid-80's and I'm sure
that most of us had our AC units just sitting there waiting to spin up
as soon as the power came back on - I know I did.

So how is that initial power requirement handled by the power
company?

Even in a relatively small outage like we had, the initial demand as
everybody's AC units, cable boxes, lights, pool filters, fans, fridges
& freezers, etc. all come on at the exact same moment must be huge.

How does the power company soften the impact on their equipment?

Generally first by staging the return of any larger sections then that's
what "spinning reserve" is for for the makeup.

Sounds good for a really large area.


Most power restores are probably not much power relative to the capacity
of the grid.

Motors and incandescents briefly draw about 6x normal current when they
are turned on.


There will be some voltage sag and short term redistribution within the
local grid as well.

Initial Power Draw After Power Outage
 

On Jul 12, 11:13*am, bud-- wrote:
On 7/11/2011 4:21 PM, dpb wrote:





On 7/11/2011 1:55 PM, DerbyDad03 wrote:
We had a power outage last night. It was in the mid-80's and I'm sure
that most of us had our AC units just sitting there waiting to spin up
as soon as the power came back on - I know I did.

So how is that initial power requirement handled by the power
company?

Even in a relatively small outage like we had, the initial demand as
everybody's AC units, cable boxes, lights, pool filters, fans, fridges
& freezers, etc. all come on at the exact same moment must be huge.

How does the power company soften the impact on their equipment?

Generally first by staging the return of any larger sections then that's
what "spinning reserve" is for for the makeup.

Sounds good for a really large area.

Most power restores are probably not much power relative to the capacity
of the grid.

Motors and incandescents briefly draw about 6x normal current when they
are turned on.





There will be some voltage sag and short term redistribution within the
local grid as well.- Hide quoted text -

- Show quoted text -- Hide quoted text -

- Show quoted text -

I usually notice a fair amount of flickering when our local elect co
restores power, as other sections are added onlne I suppose.

Initial Power Draw After Power Outage
 

I've seen delay timers on central AC, and some commercial
AC. Never seen delay timers on refrigeration equipment.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


wrote in message
...

Most AC and refrigeration equipment have a delay that
usefully takes
up to 5 min or more after power is interrupted, allowing the
pressure
in the compressor to equalize. If the pressure is not
equalized it is
likely that the compressor will try and start, but instead
draw a
large current and trip whatever high current device there is
in the
system. It is not desirable not to use the high current
limiting
device as it can shorting the life of the compressor.