BritBike Forum logo
BritBike Sponsor BritBike Sponsor BritBike Sponsor
BritBike Sponsor

BritBike Sponsor

BritBike Sponsor
BritBike Sponsor BritBike Sponsor BritBike Sponsor
  JWood Auction  
Home | Sponsors, Newsletter | Regalia | Calendar | Bike Project | BritBike Museum | Spiders Cartoons, "OLD" BritBike Forum | DVD- Manuals & Parts books | BritBike Stickers & Decals
Upgrade to: Premium Membership | Premium Life Membership | Vendor Membership | Site Sponsor Membership
Photo posting tutorial

Member Spotlight
Markus Derailius
Markus Derailius
Houston, TEXAS (Heights)
Posts: 24
Joined: December 2005
Show All Member Profiles 
Shout Box
Search eBay for motorcycle parts in following countries
Australia, Canada, France, Holland, Italy, United Kingdom, USA
Random Gallery photo
Who's Online Now
204 registered members (57nortonmodel77), 1,563 guests, and 557 spiders.
Key: Admin, Global Mod, Mod
Newest Members
Regi, Doug Baril, revans, Gilly, XTINCT
9961 Registered Users
Top Posters(30 Days)
btour 185
koan58 101
Stuart 86
NickL 69
Popular Topics(Views)
440,144 mail-order LSR
Forum Statistics
Forums33
Topics65,305
Posts632,365
Members9,961
Most Online3,995
Feb 13th, 2017
Like BritBike.com on Facebook

Previous Thread
Next Thread
Print Thread
Rate This Thread
Page 1 of 2 1 2
#707095 - 09/03/17 2:04 am Lucas Zener spec.  
Joined: Feb 2015
Posts: 258
Steven A Offline
BritBike Forum member
Steven A  Offline
BritBike Forum member

Joined: Feb 2015
Posts: 258
Melbourne Oz
Does any one know the current spec for the Lucas Zener. It is very easy to simulate them with a simple circuit.

[Linked Image]

The only question is how big to make the transistor. in this image the low power zener needs to be 13.8-0.6V

Support Your #1 BritBike Forum!
Membership Type! Free
Member
Premium
Member
Premium Life
Member
Vendor
Member
Site
Sponsor
Recognition No Premium Member Premium Life member (5 years) Vendor Member Site Sponsor Membership
Post commercial threads No No No Yes Yes
Custom title No Yes Yes Yes Yes
Upload avatar & photos No Yes Yes Yes Yes
Link avatar & photos Yes Yes Yes Yes Yes
Private Message Storage: 10 100 100 100 100
Length of signatures 255 600 600 600 600
Removes this very advert island between post 1&2 No Yes Yes Yes Yes
Price Free $12.90/year $105.00 No End
$55.00/5 years
$210.00/year
($17.50/month)
Email
Click on button >>
  Premium Member Premium Life member Vendor Member Site Sponsor Membership
#707099 - 09/03/17 2:40 am Re: Lucas Zener spec. [Re: Steven A]  
Joined: Jan 2004
Posts: 3,517
DMadigan Offline
BritBike Forum member
DMadigan  Offline
BritBike Forum member

Joined: Jan 2004
Posts: 3,517
ca, us
A 6 ampere transistor is not going to cut it. The early generators put out 120 Watts. Besides, these bikes are usually positive ground (although you can change it).

#707101 - 09/03/17 3:28 am Re: Lucas Zener spec. [Re: DMadigan]  
Joined: Feb 2015
Posts: 258
Steven A Offline
BritBike Forum member
Steven A  Offline
BritBike Forum member

Joined: Feb 2015
Posts: 258
Melbourne Oz
Originally Posted by DMadigan
A 6 ampere transistor is not going to cut it.


That's why I am asking.

Originally Posted by DMadigan
The early generators put out 120 Watts.


Do you know what the later 3 phase types produced?

Originally Posted by DMadigan
Besides, these bikes are usually positive ground (although you can change it).


This is symmetrical, just run the way you want it with an isolated heat sink.

#707104 - 09/03/17 3:53 am Re: Lucas Zener spec. [Re: Steven A]  
Joined: Mar 2014
Posts: 554
Jerry Roy Online content
BritBike Forum member
Jerry Roy  Online Content
BritBike Forum member

Joined: Mar 2014
Posts: 554
Denver CO
Amps times volts equals watts. (More or less, but close enough for government work) cool
120 watts divided by 12 V = 10 amps.
If your headlight is working, you lose that many watts, so the amps go down. But if your headlight burns out, the amps go up.
I don't like to run transistors close to their rated capacity, so 12 - 15 amps might be a better choice. Or bigger, it won't care.
With a good heat sink.
JR

#707110 - 09/03/17 7:26 am Re: Lucas Zener spec. [Re: Steven A]  
Joined: Jun 2002
Posts: 9,307
Stuart Online content
BritBike Forum member
Stuart  Online Content
BritBike Forum member

Joined: Jun 2002
Posts: 9,307
Scotland
Hi Steven,

Originally Posted by Steven A
current spec for the Lucas Zener.

12~12.5A.

Lucas supplied a single Zener in parallel with the battery and rectifier even with the '69-on RM21 alternator (rated 10.5A @ 5,000 rpm). The "headlight working" is irrelevant because, certainly in GB, we've never had a headlamp-on-in-daylight legal requirement.

Because of original Zeners' current limitation, the RM23 (14.5A @ 5,000 rpm, single-phase) was supplied with two Zeners - one connected between each AC wire and 'earth'/'ground'.

Initial oe supplies of the 3-phase RM24 to the Co-op in '79 were the 'low-output' (10.5A @ 5,000 rpm) version, so Lucas continued to supply a single Zener (but now 'negative earth/ground') in parallel with battery and rectifier.

Nevertheless, the 'high-output' (14.5A @ 5,000 rpm) version was always available. For after-market fitting to 'positive earth/ground', high-output RM24 versions were supplied with two Zeners also to be connected in parallel with battery and rectifier. However, these Zeners had to be 'matched' for Volts and Amps, Lucas originally supplied these 'matched pairs' under a different part number from the single Zeners; when Lucas stopped supplying, John Carpenter at Mistral Engineering in GB set up a test rig and continued to supply 'matched' Zeners 'til he retired.

However, when the Co-op offered the high-output RM24 as an option, and oe on the electric-start twins, Lucas supplied a 'pack' of three Zeners for connection to the AC wires. I believe this 'pack' was something off-the-shelf from a completely different application.

Btw, risking telling you something you know already, Lucas considered a Zener 'within spec.' until it allowed DC to exceed 15.5V.

Hth.

Regards,

#707152 - 09/03/17 3:11 pm Re: Lucas Zener spec. [Re: Steven A]  
Joined: Sep 2013
Posts: 1,583
quinten Online content
BritBike Forum member
quinten  Online Content
BritBike Forum member

Joined: Sep 2013
Posts: 1,583
Pacific northwest
wht am i missing, i dont see the point?

if the transistor is sized large enough

youre just moving the heat off the zener and onto the transistor.

where the transistor is working as a variable resistor.

... a power zener by its self is a simpler circuit p

#707163 - 09/03/17 4:52 pm Re: Lucas Zener spec. [Re: Steven A]  
Joined: Aug 2015
Posts: 932
Andy Higham Online content
BritBike Forum member
Andy Higham  Online Content
BritBike Forum member

Joined: Aug 2015
Posts: 932
Bolton Lancs UK
The best and most reliable way is to use a Reg/Rec from any permanent magnet alternator Japanese bike. The two alternator wires connect to two of the three ac connections (usually yellow) pos to red neg to black. This also removes the fragile plate type rectifier


1955 BSA B31 400cc "Stargazer"
1962 Greeves 200cc "Blue Meanie"
1962/67 Greeves 350cc
1967 Greeves 360cc Challenger
1984 Suzuki GSX1100 EFE "Sorcerers Apprentice"
Modified Nu-Trak GM500cc sprint/LSR bike "Deofol"
2003 Aprilia RSV Mille "Lo Stregone"
#707234 - 09/04/17 6:57 am Re: Lucas Zener spec. [Re: quinten]  
Joined: Feb 2015
Posts: 258
Steven A Offline
BritBike Forum member
Steven A  Offline
BritBike Forum member

Joined: Feb 2015
Posts: 258
Melbourne Oz
Because the zeners are expensive and seem to be "going away".

#707240 - 09/04/17 8:45 am Re: Lucas Zener spec. [Re: Steven A]  
Joined: Jan 2014
Posts: 3,324
NickL Online content
BritBike Forum member
NickL  Online Content
BritBike Forum member

Joined: Jan 2014
Posts: 3,324
Aus
The transistor will spend a lot of it's time in the semiconducting state so it's dissipation will be large.
The use of the good old 2n3055 would be a better bet but even then it'll get very hot. (IE.5 volts x 5 amps = 25watts)
Linear operation of any transistor generates heat. Pulse width modulation is far better but gets more complicated.
I posted a circuit for a single/bi phase regulator ages ago but as Andy says, you are better off
buying a ubiquitous regulator most of which use thyristors/scrs and work on the AC side as a shunt rather than on DC.
These are very good. (Just link 2 yellow wires together for single/bi phase operation.)


http://www.eBay.com.au/itm/5-Way-Regulator-Rectifier-Male-Plug-Connector-Fit-For-Honda-CB400-CBR600-DA-/162516257547?epid=907545014&hash=item25d6b94b0b:g:FD8AAOxy-gBR~G~e
http://www.eBay.com.au/itm/Voltage-Regulator-Rectifier-For-Honda-CBR600-F2-F3-CBR900RR-SC28-CBR400-NSR125-/172671240214?hash=item2834020816:g:LdsAAOSwo4pYEXPM



#707242 - 09/04/17 8:54 am Re: Lucas Zener spec. [Re: Steven A]  
Joined: Jan 2014
Posts: 3,324
NickL Online content
BritBike Forum member
NickL  Online Content
BritBike Forum member

Joined: Jan 2014
Posts: 3,324
Aus
The other thing to consider is the temperature drift on both the zener and the hfe of the transistor.

Although the Transistor has an Ic of 10 amps it's maximum heat dissipation as a to220 device is only about 40watts.



#707284 - 09/04/17 4:21 pm Re: Lucas Zener spec. [Re: Steven A]  
Joined: Jan 2004
Posts: 3,517
DMadigan Offline
BritBike Forum member
DMadigan  Offline
BritBike Forum member

Joined: Jan 2004
Posts: 3,517
ca, us
Zeners are not "going away" but the need for high power zeners as regulators has been replaced by more sophisticated circuits. Instead of using a zener, you could use a linear voltage regulator such as this 13.7 volt 1.5 ampere:
http://www.mouser.com/ds/2/389/pb137-974199.pdf
to drive the regulating transistor.
A more sophisticated circuit would use a switching driver to turn on a (presumably) IGBT during the regulating phase so the voltage drop across it is minimal, reducing heat in the transistor.
Shunt regulators are the worst as they turn on when the voltage reaches the set point (because they use SCRs) which means you loose all the power from the rest of the cycle, not just the portion that exceeds the limit.
In any case it will need a heat sink since the excess power is dissipated by heat.
Not all regulators from Japanese bikes are "plug and play". Some need a sense input. You should check on line forums for which bikes have problems with their regulators.

#707323 - 09/04/17 9:50 pm Re: Lucas Zener spec. [Re: DMadigan]  
Joined: Jan 2014
Posts: 3,324
NickL Online content
BritBike Forum member
NickL  Online Content
BritBike Forum member

Joined: Jan 2014
Posts: 3,324
Aus
Regulating on the AC side by 'shunting' the stator coil with phase angle controlled thyristors is
probably the most common method of regulating any PM type alternator. SCR's are very robust
devices and are easy to drive in such an application. Typical forward volt drop across an scr is 0.7v
so when triggered the dissipation would only be 0.7 x 5 Amps for an rm21 per thyristor (this is
in fact less as the current in the winding actually collapses when shunted so this value would be
instantaneous current) Regulating on the AC side of a PM setup is far more efficient as far as
heat dissipation is concerned and simply achieved with a couple of thyristors and a good voltage
reference. The regulator i listed above is a type i have tested extensively and will happily do 300+
watts.

Last edited by NickL; 09/10/17 11:23 pm.


#707441 - 09/05/17 9:41 pm Re: Lucas Zener spec. [Re: NickL]  
Joined: Feb 2015
Posts: 258
Steven A Offline
BritBike Forum member
Steven A  Offline
BritBike Forum member

Joined: Feb 2015
Posts: 258
Melbourne Oz
Originally Posted by NickL
The transistor will spend a lot of it's time in the semiconducting state so it's dissipation will be large.
The use of the good old 2n3055 would be a better bet but even then it'll get very hot. (IE.5 volts x 5 amps = 25watts)
Linear operation of any transistor generates heat. Pulse width modulation is far better but gets more complicated.
I posted a circuit for a single/bi phase regulator ages ago but as Andy says, you are better off
buying a ubiquitous regulator most of which use thyristors/scrs and work on the AC side as a shunt rather than on DC.
These are very good. (Just link 2 yellow wires together for single/bi phase operation.)


http://www.eBay.com.au/itm/5-Way-Regulator-Rectifier-Male-Plug-Connector-Fit-For-Honda-CB400-CBR600-DA-/162516257547?epid=907545014&hash=item25d6b94b0b:g:FD8AAOxy-gBR~G~e
http://www.ebay.com.au/itm/Voltage-Regulator-Rectifier-For-Honda-CBR600-F2-F3-CBR900RR-SC28-CBR400-NSR125-/172671240214?hash=item2834020816:g:LdsAAOSwo4pYEXPM



So this has a three phase rectifier that can be used single phase?

[Linked Image]

#707442 - 09/05/17 9:51 pm Re: Lucas Zener spec. [Re: Steven A]  
Joined: Jan 2014
Posts: 3,324
NickL Online content
BritBike Forum member
NickL  Online Content
BritBike Forum member

Joined: Jan 2014
Posts: 3,324
Aus
Correct, you can either link 2 of the 3 yellows together or cut 1 off.
Pos == Red
Neg = Green

Nick



#707477 - 09/06/17 6:02 am Re: Lucas Zener spec. [Re: NickL]  
Joined: Feb 2015
Posts: 258
Steven A Offline
BritBike Forum member
Steven A  Offline
BritBike Forum member

Joined: Feb 2015
Posts: 258
Melbourne Oz
Originally Posted by NickL
Correct, you can either link 2 of the 3 yellows together or cut 1 off.
Pos == Red
Neg = Green

Nick


Very good, I'll keep one on the shelf. Too cheap to pass up.

#713503 - 11/01/17 9:14 pm Re: Lucas Zener spec. [Re: NickL]  
Joined: Feb 2015
Posts: 258
Steven A Offline
BritBike Forum member
Steven A  Offline
BritBike Forum member

Joined: Feb 2015
Posts: 258
Melbourne Oz
Originally Posted by NickL
Correct, you can either link 2 of the 3 yellows together or cut 1 off.
Pos == Red
Neg = Green

Nick


Hi Nick. I have one on the bench. Single phase in as instructed, about 20V p-p. Out put is across 12 Ohms but with no battery present. I assume you need a battery across the output to see these things work.

[Linked Image]

#713543 - 11/02/17 3:48 am Re: Lucas Zener spec. [Re: Steven A]  
Joined: Jan 2014
Posts: 3,324
NickL Online content
BritBike Forum member
NickL  Online Content
BritBike Forum member

Joined: Jan 2014
Posts: 3,324
Aus
DON'T connect it straight across a transformer's secondary., think about what the regulator does......
The thyristors are switched on at a measured value and actually shunt the windings of you're alternator for the remainder of that cycle.
To test like you are you must place a resistor in series with the transformer winding or the full available current will be switched, thus
destroying either the regulator or the transformer. I suggest a 1-3 ohm 100w resistor.
You will need either a battery or a reasonable cap across the output to get the regulation to function, if it's not now blown up.
The ones i've tested regulate at around 14.3-14.5v.



#713544 - 11/02/17 3:51 am Re: Lucas Zener spec. [Re: Steven A]  
Joined: Jan 2014
Posts: 3,324
NickL Online content
BritBike Forum member
NickL  Online Content
BritBike Forum member

Joined: Jan 2014
Posts: 3,324
Aus
If you place you're 'scope across the input side of the unit after the resistor you will see the phase angle triggering as the regulator works.

Cap value should be around 2200uf 35v minimum.



#713637 - 11/02/17 8:06 pm Re: Lucas Zener spec. [Re: Steven A]  
Joined: Aug 2015
Posts: 932
Andy Higham Online content
BritBike Forum member
Andy Higham  Online Content
BritBike Forum member

Joined: Aug 2015
Posts: 932
Bolton Lancs UK
The latest Reg/Rec units for modern bikes are now series instead of shunt, this open circuits the windings instead of shorting them. This creates less heat and less drag


1955 BSA B31 400cc "Stargazer"
1962 Greeves 200cc "Blue Meanie"
1962/67 Greeves 350cc
1967 Greeves 360cc Challenger
1984 Suzuki GSX1100 EFE "Sorcerers Apprentice"
Modified Nu-Trak GM500cc sprint/LSR bike "Deofol"
2003 Aprilia RSV Mille "Lo Stregone"
#713662 - 11/02/17 10:48 pm Re: Lucas Zener spec. [Re: Andy Higham]  
Joined: Feb 2015
Posts: 258
Steven A Offline
BritBike Forum member
Steven A  Offline
BritBike Forum member

Joined: Feb 2015
Posts: 258
Melbourne Oz
Originally Posted by Andy Higham
The latest Reg/Rec units for modern bikes are now series instead of shunt, this open circuits the windings instead of shorting them. This creates less heat and less drag



I was wondering about that very thing. Opinion was divided in my lab but I think you are right.

#713665 - 11/02/17 11:25 pm Re: Lucas Zener spec. [Re: Steven A]  
Joined: Jan 2014
Posts: 3,324
NickL Online content
BritBike Forum member
NickL  Online Content
BritBike Forum member

Joined: Jan 2014
Posts: 3,324
Aus
Once again, think about what the shunt type regulator is doing.
In effect it is turning your PM alternator stator in a 'shorted turn' every few cycles,
this method with PM alternators is very good as it means the winding insulation is not put under pressure
by back EMF generated by 'opening' the coil as a series type would.
The instantaneous part of the shunt switching carries high current but once the turn is shorted the current and voltage collapses
so dissipated energy is small.
The operation of shunting a PM type alternator wound as simply as these ones are will probably actually reduce the 'drag' rather than increase it.
I agree on larger more complex structured windings the action could work as a brake but on these crude old things if 'drag' was increased by 10%
that would equate to 15 watts or so....................

Yes, feeding the stator winding into the front end of an SMPS with good snubbing etc is a great idea these days, but the efficiency losses would
still be greater than a parallel or shunt style unit. If the RM19/21 is 120 Watts @ 4000RPM The shunt regulator allows 100% ( in essence) output. An SMPS = 90-95%
maybe more as the input voltage varies widely with a PM unit. Cost of a shunt unit, 3 x 25A SCR's 3 phase bridge, voltage reference, comparator = 4/5 x square root of bugger all.
Complexity = Low and robustness = High.

I rest my case.

Nick

Last edited by NickL; 11/03/17 12:18 am.


#713673 - 11/03/17 12:31 am Re: Lucas Zener spec. [Re: NickL]  
Joined: Sep 2013
Posts: 1,583
quinten Online content
BritBike Forum member
quinten  Online Content
BritBike Forum member

Joined: Sep 2013
Posts: 1,583
Pacific northwest
Originally Posted by Andy Higham
The latest Reg/Rec units for modern bikes are now series instead of shunt, this open circuits the windings instead of shorting them. This creates less heat and less drag


there is minimal drag when the stator is shorted/shunted ... .
why ? because no electromotive work is ask to be done .
there is no electrical circuit , there is no end of any wire in which to measure a voltage differential ... its magnetic

there is just this lump of copper and iron and the eddy current heat , same as normal .
nothing extra in the way of heat (drag) is coming from the induced magnetic field
because no work is being done .
the stator isn't
fighting the rotor so much ,
because the stator is safely unloaded and sort of freewheeling on minimal magnetic inertia ... out of phase with the rotor .

conversely , when a stator is open-shunted the induced open voltages can climb to levels higher
than the magnet insulation wire can handle ... open shunting is for stators specifically designed to handle the application

#713698 - 11/03/17 7:30 am Re: Lucas Zener spec. [Re: quinten]  
Joined: Feb 2015
Posts: 258
Steven A Offline
BritBike Forum member
Steven A  Offline
BritBike Forum member

Joined: Feb 2015
Posts: 258
Melbourne Oz
Originally Posted by quinten
Originally Posted by Andy Higham
The latest Reg/Rec units for modern bikes are now series instead of shunt, this open circuits the windings instead of shorting them. This creates less heat and less drag


there is minimal drag when the stator is shorted/shunted ... .
why ? because no electromotive work is ask to be done .
there is no electrical circuit , there is no end of any wire in which to measure a voltage differential ... its magnetic

there is just this lump of copper and iron and the eddy current heat , same as normal .
nothing extra in the way of heat (drag) is coming from the induced magnetic field
because no work is being done .
the stator isn't
fighting the rotor so much ,
because the stator is safely unloaded and sort of freewheeling on minimal magnetic inertia ... out of phase with the rotor .

conversely , when a stator is open-shunted the induced open voltages can climb to levels higher
than the magnet insulation wire can handle ... open shunting is for stators specifically designed to handle the application


Not so sure that shorting the windings does not cause drag. I have a vague memory of doing this in a lab and there was an awful lot of resistant to rotation. It's to do with magnetically generated reverse torque.

A linear analogue is dropping a magnet down a metal tube. It goes pretty slow despite gravity.

#713730 - 11/03/17 4:29 pm Re: Lucas Zener spec. [Re: Steven A]  
Joined: Aug 2015
Posts: 932
Andy Higham Online content
BritBike Forum member
Andy Higham  Online Content
BritBike Forum member

Joined: Aug 2015
Posts: 932
Bolton Lancs UK
"there is no electrical circuit" There is an electrical circuit, the shunted winding is a circuit.
Try this experiment, take a small permanent magnet electric motor and turn the shaft with your fingers. You will feel the pull of the magnet on the armature poles. Now short the terminals together and you fill feel it is harder to turn. An electric motor and an alternator are essentially the same thing.
It is common practice to use shunt resistors including zero ohms and to brake a motor


1955 BSA B31 400cc "Stargazer"
1962 Greeves 200cc "Blue Meanie"
1962/67 Greeves 350cc
1967 Greeves 360cc Challenger
1984 Suzuki GSX1100 EFE "Sorcerers Apprentice"
Modified Nu-Trak GM500cc sprint/LSR bike "Deofol"
2003 Aprilia RSV Mille "Lo Stregone"
#713781 - 11/04/17 12:29 am Re: Lucas Zener spec. [Re: Steven A]  
Joined: Jan 2014
Posts: 3,324
NickL Online content
BritBike Forum member
NickL  Online Content
BritBike Forum member

Joined: Jan 2014
Posts: 3,324
Aus
Andy, dynamic breaking on a drive cannot be compared in the slightest to shunting a 6 pole 120 watt crude old PM alternator like these.
Regenerative braking or dynamic braking from freewheeling motors with many more turns and in the case of PM motors, much higher flux magnets
is like comparing chalk and cheese.

With something such as a high efficiency Multi helical winding on the stator with a 1-3 thou air gap like they use on small windmill generators,
i appreciate that you will brake the rotor by shorting the stator windings, i have made a few controls for these applications and have found this.
Likewise if similar winding types are being used to increase capacity on late bikes, yes a drag/braking effect will ensue.

I doubt you get any measurable more drag with this old junk by shunting the stator. You are creating a shorted turn on a very small winding, that
in effect reduces the induction to next to nothing. If you set up a rig and prove that more than 150 watts or so is being consumed by the driven shunted
stator i would be very surprised. My own old jig that i used when building regulators only has a 0.37kw motor/inverter and that was never heavily loaded.

Also, if you wish to use old Brit alternators with series regulators i suggest you put a couple of back to back large zeners across the windings to limit
the voltage when they are switched whilst rotating, 24v will do, or have a stator made up with higher voltage insulation on the winding.

Anyway i guess you guys all know a lot more about this stuff than me, so i'll let it rest.

Nick



Page 1 of 2 1 2

Moderated by  Alan_nc 


Home | Sponsors | Newsletter | Regalia | Calendar | Bike Project | BritBike Museum | Spiders Cartoons | "OLD" BritBike Forum | DVD- Manuals & Parts books | BritBike Stickers & Decals
Upgrade to: Premium Membership | Premium Life Membership | Vendor Membership | Site Sponsor Membership
UBB.threads™ PHP Forum Software 7.6.0
Page Time: 0.460s Queries: 16 (0.064s) Memory: 1.0007 MB (Peak: 1.3627 MB) Zlib disabled. Server Time: 2017-11-24 23:57:01 UTC