I've got an office with some servers on a UPS. From time to time, the
UPS is reporting issues with the mains power quality and switching to
battery. It then typically switches back soon after, but sometimes the
RCBO for that circuit trips at the same time.

I'm looking for something that can monitor the power quality, so I can
try to isolate the problem. Does anyone know of monitoring equipment
that can monitor the quality of mains power over a period of time? I
guess something that just measured voltage would be a start.

I've got a multimeter, but it only shows the instant reading and can't
record data. And these events only occur once a week or so, and seem
to be random.

Caecilius wrote:

I'm looking for something that can monitor the power quality

I've got an old Seaward Mains Disturbance Recorder

You leave it plugged in, it counts the number of transients, and has
LEDs to indicate if the voltage has been out of range (mine's the old
240V +/- 6%, presume they are now calibrated for 230V +/- 10%) and if
there's been a brownout for more than 1/2 a cycle, or 2 cycles.

http://www.rnelectronics.com/meters/seaward-dr500-mains-supply-disturbance-recorder/flypage-ask.tpl.html

On Mon, 19 Aug 2013 12:33:56 +0100, Andy Burns wrote:

I'm looking for something that can monitor the power quality

Does your UPS not measure the volts and allow you to poll it for that
information?

You leave it plugged in, it counts the number of transients, and has
LEDs to indicate if the voltage has been out of range (mine's the old
240V +/- 6%, presume they are now calibrated for 230V +/- 10%)

Shouldn't be the spec never actually changed to +/- 10%. It's still
230 V +10% -6% (216 - 253 V).

--
Cheers
Dave.

Dave Liquorice wrote:

the spec never actually changed to +/- 10%. It's still
230 V +10% -6% (216 - 253 V).

I know te supply was +10%/-6% but I thought it had eventually changed
(nominally) to +/-10%, or is it that appliances have to be designed to
accept +/-10% now?

On Mon, 19 Aug 2013 13:26:38 +0100 (BST), "Dave Liquorice"
wrote:

Does your UPS not measure the volts and allow you to poll it for that
information?

It probably does. It's got a network card, sends email alerts, and I
think it supports SNMP. I'll look into this.

I had an event early Sunday morning, which resulted in the following
emails (the contents of the emails doesn't really add anything):

Subject: UPS: On battery power in response to rapid change of input.
Date: Sun, 18 Aug 2013 00:27:14

Subject: UPS: No longer on battery power.
Date: Sun, 18 Aug 2013 00:27:15

The RCBO didn't trip this time.

One advantage of a monitor is that I could plug it into other outlets
and see if it's ocurring on multiple rings/outlets or if it's just
one.

You leave it plugged in, it counts the number of transients, and has
LEDs to indicate if the voltage has been out of range (mine's the old
240V +/- 6%, presume they are now calibrated for 230V +/- 10%)

Shouldn't be the spec never actually changed to +/- 10%. It's still
230 V +10% -6% (216 - 253 V).

On 19/08/2013 12:19, Caecilius wrote:
I've got an office with some servers on a UPS. From time to time, the
UPS is reporting issues with the mains power quality and switching to
battery. It then typically switches back soon after, but sometimes the
RCBO for that circuit trips at the same time.

I'm looking for something that can monitor the power quality, so I can
try to isolate the problem. Does anyone know of monitoring equipment
that can monitor the quality of mains power over a period of time? I
guess something that just measured voltage would be a start.

I've got a multimeter, but it only shows the instant reading and can't
record data. And these events only occur once a week or so, and seem
to be random.


In my office, I had to change the 16A MCB for a type C, as that would
always trip on mains power restore if there was a power cut, which was
kind of annoying! - It had a 3KvA UPS' on it, plus some other small non
essential IT equipment we could live without during a power cut, so you
might want to look at replacing the RCBO with a type C to stop it
happening to yours too.

--
Toby...
Remove your pants to reply

On Mon, 19 Aug 2013 14:45:15 +0100, Toby
wrote:
In my office, I had to change the 16A MCB for a type C, as that would
always trip on mains power restore if there was a power cut, which was
kind of annoying! - It had a 3KvA UPS' on it, plus some other small non
essential IT equipment we could live without during a power cut, so you
might want to look at replacing the RCBO with a type C to stop it
happening to yours too.

I'm pretty sure it's the RCD part of the RCBO that's tripping though,
so I don't think changing from a "B" to a "C" will make any difference
because that's just the MCB part.

Originally, I had six circuits (2 x B32 and 4 x B6) on one RCD, and
that RCD was occasionally tripping. I never had any MCBs trip. I
suspected the B32 circuit with the UPS/Servers on it, but wasn't sure,
so I swapped out both B32 MCBs for RCBOs, and now the B32 RCBO for the
UPS/servers circuit trips and nothing else.

On Mon, 19 Aug 2013 14:45:15 +0100, Toby wrote:

It then typically switches back soon after, but sometimes the RCBO
for
that circuit trips at the same time.

In my office, I had to change the 16A MCB for a type C, as that would
always trip on mains power restore if there was a power cut,

RCBO MCB ...

IT/electronic kit tends to leak rather a lot to earth because of the
filters on the mains input to keep all the nasty RF interference off
the mains cabling. IIRC it's not recomended to have more than 10 such
appliances on a single RCD.

Switching transients may well create enough earth leakage current to
push an RCBO that is already near its leakage limit past the leakage
trip point.

It could be a switching surge that a type C MCB would help with.

--
Cheers
Dave.

On Mon, 19 Aug 2013 13:58:53 +0100, Andy Burns wrote:

... the spec never actually changed to +/- 10%. It's still 230 V
+10%
-6% (216 - 253 V).

I know te supply was +10%/-6% but I thought it had eventually changed
(nominally) to +/-10%, or is it that appliances have to be designed to
accept +/-10% now?

There was a date given to change to +/- 10% spec and appliances, a
date several years ago but I'm fairly sure that any action on that
date got quietly dropped and we (and Europe) have remained on the 230
+10% -6%.

230 +/-10% is 207 to 253 and a heck of range for kit to deal with.

--
Cheers
Dave.

On Mon, 19 Aug 2013 15:09:29 +0100 (BST), "Dave Liquorice"
wrote:
IT/electronic kit tends to leak rather a lot to earth because of the
filters on the mains input to keep all the nasty RF interference off
the mains cabling. IIRC it's not recomended to have more than 10 such
appliances on a single RCD.

Switching transients may well create enough earth leakage current to
push an RCBO that is already near its leakage limit past the leakage
trip point.

That's what I suspect I may be seeing. Perhaps the UPS contains MOVs
which snub spikes to earth, so noise on the supply causes earth
leakage which trips the RCD.

On 19/08/2013 12:19, Caecilius wrote:
I've got an office with some servers on a UPS. From time to time, the
UPS is reporting issues with the mains power quality and switching to
battery. It then typically switches back soon after, but sometimes the
RCBO for that circuit trips at the same time.

I'm looking for something that can monitor the power quality, so I can
try to isolate the problem. Does anyone know of monitoring equipment
that can monitor the quality of mains power over a period of time? I
guess something that just measured voltage would be a start.

I've got a multimeter, but it only shows the instant reading and can't
record data. And these events only occur once a week or so, and seem
to be random.

A really DIY approach would be to feed the output of mains transformer,
possibly via a potentiometer, into the audio line-in socket of a PC. A
wall-wart with an AC output (rare, but they do exist) would probably
satisfy most safety concerns. You could record the waveform with audio
software of your choice, presumably at a fairly low sampling rate. I'm
not sure whether a typical integrated soundcard can go as low as 50Hz
though.

On 19/08/2013 18:26, MrWeld wrote:
On 19/08/2013 12:19, Caecilius wrote:
I've got an office with some servers on a UPS. From time to time, the
UPS is reporting issues with the mains power quality and switching to
battery. It then typically switches back soon after, but sometimes the
RCBO for that circuit trips at the same time.

I'm looking for something that can monitor the power quality, so I can
try to isolate the problem. Does anyone know of monitoring equipment
that can monitor the quality of mains power over a period of time? I
guess something that just measured voltage would be a start.

I've got a multimeter, but it only shows the instant reading and can't
record data. And these events only occur once a week or so, and seem
to be random.

A really DIY approach would be to feed the output of mains transformer,
possibly via a potentiometer, into the audio line-in socket of a PC. A
wall-wart with an AC output (rare, but they do exist) would probably
satisfy most safety concerns. You could record the waveform with audio
software of your choice, presumably at a fairly low sampling rate. I'm
not sure whether a typical integrated soundcard can go as low as 50Hz
though.


the range of human hearing is 20Hz to 20 KHz and many sound cards
support LFE (Low frequency extensions) so I'd expect the sound card
approach to work.

In addition, subtracting a synchronised 50Hz sinusoidal signal from the
recorded signal will then give you a signal containing just the bad
quality stuff.

On Mon, 19 Aug 2013 18:26:52 +0100, MrWeld MrWeld wrote:
A really DIY approach would be to feed the output of mains transformer,
possibly via a potentiometer, into the audio line-in socket of a PC. A
wall-wart with an AC output (rare, but they do exist) would probably
satisfy most safety concerns. You could record the waveform with audio
software of your choice, presumably at a fairly low sampling rate. I'm
not sure whether a typical integrated soundcard can go as low as 50Hz
though.

That's an interesting thought. Mains transformers are easy enough to
find, or as you say an AC PSU. Maybe I can use a low-end CPU device
instead of a PC to keep it low-power: the raspberry pi doesn't have
audio in, but the pandaboard es does. If I've got time I might give
that a go.

Maybe there are cheap ADCs with USB or serial outputs I could use.
This is getting interesting. Thanks for the idea.

On Mon, 19 Aug 2013 18:31:03 +0100, Steve wrote:

the range of human hearing is 20Hz to 20 KHz and many sound cards
support LFE (Low frequency extensions)

Low Frequency Effects, the bangs and thumps. Don't think it goes any
lower than the other five channels that are full bandwidth. The LFE
has an uuper frequency limit around a few hundred Hz. Just means you
have signal to augment the existing LF in the main channels by giving
it a bit of welly into decent sub-woofers.

But any sound card ought to cope with 50 Hz no problem.

--
Cheers
Dave.

On Mon, 19 Aug 2013 16:51:55 +0100, Caecilius wrote:

Switching transients may well create enough earth leakage current
to
push an RCBO that is already near its leakage limit past the
leakage
trip point.

That's what I suspect I may be seeing. Perhaps the UPS contains MOVs
which snub spikes to earth, so noise on the supply causes earth
leakage which trips the RCD.

MOVs breakdown at quite high voltages so a bit of "noise" won't
trigger them.

I'm thinking of a interuption and possible phase change when the UPS
switches from it's internal frequency back to mains causing the
capacitors in the filters to charge/discharge all at once thus
dumping or pulling current via the earth. An RCD is only looking for
an imbalance between L and N it doesn't care if that imbalance
current leaking to earth or current leaking from earth...

--
Cheers
Dave.

On Mon, 19 Aug 2013 18:26:52 +0100, MrWeld wrote:

On 19/08/2013 12:19, Caecilius wrote:
I've got an office with some servers on a UPS. From time to time, the
UPS is reporting issues with the mains power quality and switching to
battery. It then typically switches back soon after, but sometimes the
RCBO for that circuit trips at the same time.

I'm looking for something that can monitor the power quality, so I can
try to isolate the problem. Does anyone know of monitoring equipment
that can monitor the quality of mains power over a period of time? I
guess something that just measured voltage would be a start.

I've got a multimeter, but it only shows the instant reading and can't
record data. And these events only occur once a week or so, and seem to
be random.

A really DIY approach would be to feed the output of mains transformer,
possibly via a potentiometer, into the audio line-in socket of a PC. A
wall-wart with an AC output (rare, but they do exist) would probably
satisfy most safety concerns. You could record the waveform with audio
software of your choice, presumably at a fairly low sampling rate. I'm
not sure whether a typical integrated soundcard can go as low as 50Hz
though.

I'm not sure how well very fast transient spikes would pass through a
mains transformer with its large number of turns and magnetic properties
that obviously favour mains frequency.

A divider that consists of resistors only would provide an accurate view
of the situation, but safety and isolation could then be a problem.

On 19/08/13 19:56, Caecilius wrote:
On Mon, 19 Aug 2013 18:26:52 +0100, MrWeld MrWeld wrote:
A really DIY approach would be to feed the output of mains transformer,
possibly via a potentiometer, into the audio line-in socket of a PC. A
wall-wart with an AC output (rare, but they do exist) would probably
satisfy most safety concerns. You could record the waveform with audio
software of your choice, presumably at a fairly low sampling rate. I'm
not sure whether a typical integrated soundcard can go as low as 50Hz
though.
That's an interesting thought. Mains transformers are easy enough to
find, or as you say an AC PSU. Maybe I can use a low-end CPU device
instead of a PC to keep it low-power: the raspberry pi doesn't have
audio in, but the pandaboard es does. If I've got time I might give
that a go.

Maybe there are cheap ADCs with USB or serial outputs I could use.
This is getting interesting. Thanks for the idea.
Arduino has ADC at fairly low quality (8 bit I think)


--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to lead are elected by the least capable of producing, and where the members of society least likely to sustain themselves or succeed, are rewarded with goods and services paid for by the confiscated wealth of a diminishing number of producers.

"Dave Liquorice" wrote in message
ll.co.uk...
On Mon, 19 Aug 2013 13:58:53 +0100, Andy Burns wrote:

... the spec never actually changed to +/- 10%. It's still 230 V
+10%
-6% (216 - 253 V).

I know te supply was +10%/-6% but I thought it had eventually changed
(nominally) to +/-10%, or is it that appliances have to be designed to
accept +/-10% now?

There was a date given to change to +/- 10% spec and appliances, a
date several years ago but I'm fairly sure that any action on that
date got quietly dropped and we (and Europe) have remained on the 230
+10% -6%.

230 +/-10% is 207 to 253 and a heck of range for kit to deal with.

--
Cheers
Dave.



Depends on the kit. A lot of stuff like TVs that would in the past have not
enjoyed the mains fluctuating over these sorts of limits, now use SMPS with
a PFC front end that doesn't care from 90 volts to 260 volts, allowing the
same supply to be used world-wide. Many of these multi-stage switchers will
actually start up at voltages as low as 30 volts

Arfa

"steve" wrote in message
...
On Mon, 19 Aug 2013 18:26:52 +0100, MrWeld wrote:

On 19/08/2013 12:19, Caecilius wrote:
I've got an office with some servers on a UPS. From time to time, the
UPS is reporting issues with the mains power quality and switching to
battery. It then typically switches back soon after, but sometimes the
RCBO for that circuit trips at the same time.

I'm looking for something that can monitor the power quality, so I can
try to isolate the problem. Does anyone know of monitoring equipment
that can monitor the quality of mains power over a period of time? I
guess something that just measured voltage would be a start.

I've got a multimeter, but it only shows the instant reading and can't
record data. And these events only occur once a week or so, and seem to
be random.

A really DIY approach would be to feed the output of mains transformer,
possibly via a potentiometer, into the audio line-in socket of a PC. A
wall-wart with an AC output (rare, but they do exist) would probably
satisfy most safety concerns. You could record the waveform with audio
software of your choice, presumably at a fairly low sampling rate. I'm
not sure whether a typical integrated soundcard can go as low as 50Hz
though.

I'm not sure how well very fast transient spikes would pass through a
mains transformer with its large number of turns and magnetic properties
that obviously favour mains frequency.

A divider that consists of resistors only would provide an accurate view
of the situation, but safety and isolation could then be a problem.



Two X rated caps in series ahead of the resistive divider ?

Arfa

Caecilius wrote:
I've got an office with some servers on a UPS. From time to time, the
UPS is reporting issues with the mains power quality and switching to
battery. It then typically switches back soon after, but sometimes the
RCBO for that circuit trips at the same time.

I'm looking for something that can monitor the power quality, so I can
try to isolate the problem. Does anyone know of monitoring equipment
that can monitor the quality of mains power over a period of time? I
guess something that just measured voltage would be a start.

I've got a multimeter, but it only shows the instant reading and can't
record data. And these events only occur once a week or so, and seem
to be random.



http://www.ebay.com.au/itm/Hantek-36...item35ca03acc3

On Mon, 19 Aug 2013 23:34:46 +0100, The Natural Philosopher
wrote:

Maybe there are cheap ADCs with USB or serial outputs I could use.
This is getting interesting. Thanks for the idea.
Arduino has ADC at fairly low quality (8 bit I think)

Yes, that looks possible. Arduino nano has a 10-bit ADC with a sample
time of 100us. More than enough for this task I think. The only
poblen I can see is that the arduino doesn't have much storage so it
would need to log to something else.

On Tue, 20 Aug 2013 08:28:15 +0100, Caecilius wrote:

On Mon, 19 Aug 2013 23:34:46 +0100, The Natural Philosopher
wrote:

Maybe there are cheap ADCs with USB or serial outputs I could use.
This is getting interesting. Thanks for the idea.
Arduino has ADC at fairly low quality (8 bit I think)

Yes, that looks possible. Arduino nano has a 10-bit ADC with a sample
time of 100us. More than enough for this task I think. The only
poblen I can see is that the arduino doesn't have much storage so it
would need to log to something else.

SD card. Libraries to do this are readily available.


--

En el artículo , Caecilius
escribió:

Subject: UPS: On battery power in response to rapid change of input.
Date: Sun, 18 Aug 2013 00:27:14

You've got an APC unit.

With a message like that, I'd be looking for a loose connection
somewhere between the consumer unit and the socket it's plugged into.

--
(\_/)
(='.'=)
(")_(")

On Wed, 21 Aug 2013 03:43:39 +0100, Mike Tomlinson
wrote:

En el artículo , Caecilius
escribió:

Subject: UPS: On battery power in response to rapid change of input.
Date: Sun, 18 Aug 2013 00:27:14

You've got an APC unit.

With a message like that, I'd be looking for a loose connection
somewhere between the consumer unit and the socket it's plugged into.

Looking around the web, it seems this means that the rate of voltage
change on the input was too high. It could be loose connection, but it
could also just be the utility voltage changing too fast. It does
change throughout the day, between about 220v and 235v (I'm monitoring
the SNMP stats).

I've reduced the sensitibity from "normal" to "reduced", as everything
it's powering have switched-mode power supplies so don't really care
too much about the input voltage or it's rate of change.

In article , Caecilius
writes

I've reduced the sensitibity from "normal" to "reduced", as everything
it's powering have switched-mode power supplies so don't really care
too much about the input voltage or it's rate of change.

That's a good idea, I've done the same thing on a remote site where
mains power is iffy. You'll still get the warnings in the UPS logs,
but it will no longer switch to battery as readily.

--
(\_/)
(='.'=)
(")_(")

On Monday, 19 August 2013 12:19:14 UTC+1, Caecilius wrote:
I've got an office with some servers on a UPS. From time to time, the
UPS is reporting issues with the mains power quality and switching to
battery. It then typically switches back soon after, but sometimes the
RCBO for that circuit trips at the same time.

I'm looking for something that can monitor the power quality, so I can
try to isolate the problem. Does anyone know of monitoring equipment
that can monitor the quality of mains power over a period of time? I
guess something that just measured voltage would be a start.

I've got a multimeter, but it only shows the instant reading and can't
record data. And these events only occur once a week or so, and seem
to be random.