Re: D1D40 SSR's burning out?? Don't use a diode! [TANKS]

["flier" <FLIER-at-sbcglobal.net>]

Whoa Grant!  My mistake.  Don't use a diode on your 
motors!

For some reason it totally slipped my mind we're 
talking reversing motors.  You'd be fine in one 
direction but the other would definately cause some 
smoke...when the diode shorted.

I think if you heatsink your SSRs properly you'll be 
fine.  I need to let the Anvilus designer comment on 
the necessity of including clamping diodes anywhere 
as I don't think it's been a problem up to now.  The 
Anvilus controller actually uses back EMF for braking 
force when switching motor direction.  The software 
is timed to take advantage.

Sorry for the oversight!

Ted


--- Original Message ---
From: Grant Mahalek <gmahalek-at-shaw.ca>
To: tanks-at-rctankcombat.com
Subject: Re: D1D40 SSR's burning out?? [TANKS]

>Ted,
>
>Awesome advice....I really apppreciate the detailed 
suggestions.  Now this 
>is news I can use....
>
>I'am operating my system at 24vdc. So I suppose I 
would be looking for a 
>fast switching diode of 1A with a voltage rating of 
about 24-40V. So a 24 - 
>40V 1A fast switching diode connected right across 
the motor should protect 
>the SSR's from being burned out by back EMF?
>
>When you say install the diode "right across the 
motor...", do you mean 
>splice the diode directly into the positive and 
negative wires leading into 
>the motor(ie.- as close to the motor as possible).  
Should the diode be 
>installed in any particular direction? Can the diode 
be installed at the 
>terminal block on the motor controller where the 
postive and negative leads 
>connect from the motors?
>
>I'll go down to the local electronics store and pick 
up some cooling fans as 
>soon as I hear back from you.
>
>Regards,
>
>Grant
>
>
>----- Original Message ----- 
>From: "flier" <FLIER-at-sbcglobal.net>
>To: <tanks-at-rctankcombat.com>; 
<tanks-at-rctankcombat.com>
>Sent: Thursday, November 03, 2005 1:19 PM
>Subject: Re: D1D40 SSR's burning out?? [TANKS]
>
>
>> Hey Grant,
>>
>> If the motors stall, the current will go to the 
max.
>> I'm assuming the 15.4A spec is the typical current
>> the motor will draw at a specified torque and at 
some
>> duty cycle.  You may very well be coming close or
>> exceeding the 40A rating of the SSRs if the motor 
is
>> being 'held back'.  The D1D40 gets hot as heck
>> dissipating the full 40A so they have to be mounted
>> on a heatsink and may even need some cooling 
airflow
>> to switch the full spec 40A.  Check out the D1D40
>> heatsink specs.  Even at 15 amps or so they're 
gonna
>> get up to 140 deg C!  Beyond 15A they must have a
>> heatsink.
>>
>> In a nutshell, protection diodes keep the SSRs from
>> seeing back EMF from an inductive load like a 
motor.
>> When the SSR breaks the circuit, the motor has some
>> stored energy in it's coils that instantaneously
>> feeds back to the open circuit.  The diode keeps 
the
>> SSR from seeing that spike.  Just pick a fast
>> switching diode say 1A with a voltage rating that's
>> at least equal or a little greater than your supply
>> voltage.  If 12V, then a 20V 1A switching diode 
will
>> work.  It goes right across the motor.
>>
>> Take care,
>>
>> Ted
>>
>> --- Original Message ---
>> From: Grant Mahalek <gmahalek-at-shaw.ca>
>> To: tanks-at-rctankcombat.com
>> Subject: Re: D1D40 SSR's burning out?? [TANKS]
>>
>>>Hey Ted,
>>>
>>>Thanks for the input Ted. I do not have 
any "protect
>> diodes" installed in
>>>the circuit.  Are you referring to the "Transient
>> Protection" using fast
>>>recovery diodes with PIV rated greater than the
>> supply voltage as
>>>illustrated/described on the www.crydom.com
>> website.  Can you suggest what
>>>type and size of diode to use and how/where to
>> install these diodes.
>>>
>>>I'am assuming when you say "dissipation/max draw
>> issue" you mean the motor/s
>>>are drawing in excess of 40 amps which may be
>> burning out the D1D40 SSR's.
>>>The motors are only rated at 24vdc, 15.4 amps. I've
>> taken the drive system
>>>apart....without the tracks or motor connected the
>> gear reduction runs
>>>freely. In the field tests where the SSR's burned
>> out I was using boat
>>>roller drive wheels....this did'nt work.....the
>> drive wheels slipped even
>>>when I had the tracks so tight the 1/2" drive-
shafts
>> were bending under the
>>>load.
>>>
>>>Could you please explain what you mean
>> by "dissipation.....issue"? Any
>>>suggestions how this problem could be corrected?
>>>
>>>Oh, one last thing, I was talking with an
>> Electronics Technician yesterday
>>>in the LHS, he feels there may be a problem with 
max
>> current draw and
>>>suggested installing resistors to limit the current
>> flowing to the motors.
>>>What do you think? Don't know what type or size or
>> exactly where/how to
>>>install.  Do you have any suggestions?
>>>
>>>Don't hesitate to provide technical answers as my
>> buddy Mark Townsend, a
>>>skilled electronics hobbyist is helping me out.
>>>
>>>I'am building new drive wheels today using plywood
>> discs and rubber bungee
>>>cord ie.-obviously a more successful design). I 
will
>> be measuring the no
>>>load and full load(ie.-transmission and tracks
>> installed) current on the
>>>bench today or tomorrow.
>>>
>>>Thanks again, any ideas are appreciated!
>>>
>>>
>>>Grant "thank goodnes for people more knowledgeable
>> than me" Mahalek
>>>
>>>
>>>----- Original Message ----- 
>>>From: "flier" <FLIER-at-sbcglobal.net>
>>>To: <tanks-at-rctankcombat.com>
>>>Sent: Thursday, November 03, 2005 8:44 AM
>>>Subject: Re: D1D40 SSR's burning out?? [TANKS]
>>>
>>>
>>>> Hey Grant, it's Ted Callahan.
>>>>
>>>> If your max current is significantly below 40A,
>> then the prob may be back
>>>> EMF where the protect diodes come in although I'm
>> skeptical.  I think you
>>>> may have a dissipation/max draw issue.
>>>>
>>>> Regards,
>>>> Ted
>>>>
>>>> --- Original Message ---
>>>> From: Grant Mahalek <gmahalek-at-shaw.ca>
>>>> To: tanks-at-rctankcombat.com
>>>> Subject: Re: D1D40 SSR's burning out?? [TANKS]
>>>>
>>>>>Flier,
>>>>>
>>>>>Thanks for the suggestion.  I will be measuring
>> the max current draw
>>>>>today.
>>>>>Oh by the way, what's your name....I'd like to
>> address you by your name.
>>>>>
>>>>>Grant "I'am learning every day" Mahalek
>>>>>
>>>>>
>>>>>----- Original Message ----- 
>>>>>From: "flier" <FLIER-at-sbcglobal.net>
>>>>>To: <tanks-at-rctankcombat.com>;
>> <tanks-at-rctankcombat.com>
>>>>>Sent: Wednesday, November 02, 2005 7:15 AM
>>>>>Subject: Re: D1D40 SSR's burning out?? [TANKS]
>>>>>
>>>>>
>>>>>> Grant,
>>>>>>
>>>>>> Have you measured your max current draw?
>>>>>>
>>>>>>
>>>>>> --- Original Message ---
>>>>>> From: Grant Mahalek <gmahalek-at-shaw.ca>
>>>>>> To: tanks-at-rctankcombat.com
>>>>>> Subject: Re: D1D40 SSR's burning out?? [TANKS]
>>>>>>
>>>>>>>Hi Norm,
>>>>>>>
>>>>>>>In Test #1 the right SSR got very hot.
>>>>>>>
>>>>>>>I forgot to check the SSR temperatures in 
Test#2.
>>>>>>>
>>>>>>>Grant
>>>>>>>  ----- Original Message -----=20
>>>>>>>  From: Norman Wieser=20
>>>>>>>  To: tanks-at-rctankcombat.com=20
>>>>>>>  Sent: Tuesday, November 01, 2005 9:08 PM
>>>>>>>  Subject: Re: D1D40 SSR's burning out?? 
[TANKS]
>>>>>>>
>>>>>>>
>>>>>>>  Hi Grant
>>>>>>>
>>>>>>>   Did the SSR's get very Hot ?
>>>>>>>
>>>>>>>  Norm
>>>>>>>    ----- Original Message -----=20
>>>>>>>    From: Grant Mahalek=20
>>>>>>>    To: tanks-at-rctankcombat.com=20
>>>>>>>    Sent: Tuesday, November 01, 2005 6:27 PM
>>>>>>>    Subject: Fw: D1D40 SSR's burning out??
>> [TANKS]
>>>>>>>
>>>>>>>
>>>>>>>    Hi there,
>>>>>>>
>>>>>>>    I've run into a bit of a problem in the
>>>>>> construction of my Hetzer.  =
>>>>>>>I've burned out three Crydom SSR's with my
>> Anvilus
>>>>>> proportional motor =
>>>>>>>controller.  I've sent off an email to
>>>>>> www.crydom.com today in hopes of =
>>>>>>>getting some suggestions.  The Crydom website
>>>>>> mentions something called =
>>>>>>>"Transient Protection" and protection of the
>> SSR's
>>>>>> using fast recovery =
>>>>>>>type diodes with PIV rated greater than supply 
=
>>>>>>>voltage(....cool....unfortunately I don't
>> completely
>>>>>> understand this). =
>>>>>>>Has anyone out there
>>>>>>>
>>>>>>>    In the "Tri-Pact News Service" article
>>>>>> entitled "R/C Combat Vehicles =
>>>>>>>Speed Controls" under the section "Other 
Issues"
>>>>>> various devices are =
>>>>>>>recommended to limit power surges and radio
>>>>>> interference.  After a small =
>>>>>>>fix(installation of a CMOS NAND 4011 Gate) into
>> the
>>>>>> steering and =
>>>>>>>throttle servo leads, radio interference is no
>>>>>> longer a problem.
>>>>>>>
>>>>>>>    However, burning out these SSR's is 
becoming
>> a
>>>>>> bit of a =
>>>>>>>pain....xxo!!/?##.
>>>>>>>
>>>>>>>    Can anyone out there offer suggestions,
>> detailed
>>>>>> or otherwise on how =
>>>>>>>to overcome this obstacle?  Any suggestions
>> would be
>>>>>> much appreciated.
>>>>>>>
>>>>>>>    Oh, by the way, the rubber boat roller 
drive
>>>>>> wheels did not work, =
>>>>>>>the rubber was too hard and the drive wheels
>> slipped
>>>>>> in the tracks.  =
>>>>>>>I'am going to use the "tried and true" TTS 
rubber
>>>>>> bungee cord wrapped =
>>>>>>>plywood drive wheels.  And for those of you
>>>>>> wondering about what =
>>>>>>>thickness of drive-shaft to use, I support 
Steve
>>>>>> Tyng's suggestion to =
>>>>>>>use a hardened steel shaft > 1/2 inch.  I've
>> already
>>>>>> bent both my 1/2 =
>>>>>>>inch drive shafts in the minimal testing I've
>> done
>>>>>> so far.
>>>>>>>
>>>>>>>    Supper call....thanks for any help you guys
>> can
>>>>>> offer.
>>>>>>>
>>>>>>>
>>>>>>>    Grant P. Mahalek
>>>>>>>
>>>>>>>    ----- Original Message -----=20
>>>>>>>    From: Grant Mahalek=20
>>>>>>>    To: support-at-crydom.com=20
>>>>>>>    Sent: Tuesday, November 01, 2005 7:33 AM
>>>>>>>    Subject: D1D40 SSR's burning out??
>>>>>>>
>>>>>>>
>>>>>>>    Hello there,
>>>>>>>
>>>>>>>
>>>>>>>    I'am a hobbyist using a pair of Crydom 
D1D40
>>>>>> SSR's with a motor =
>>>>>>>controller to provide proportional speed 
control
>> for
>>>>>> a custom built 1:6 =
>>>>>>>scale radio control combat tank. The motor
>> controller
>>>>>> (Anvilus RC Relay =
>>>>>>>SSR Motor Controller; Board h_050412, Manual
>> 050425)
>>>>>> is described in =
>>>>>>>detail at www.anvilus.com . The motor and 
control
>>>>>> system is wired =
>>>>>>>according to figure 3, page 5 of the manual.
>> I'am
>>>>>> using a pair of new =
>>>>>>>electric scooter motors(MY1016) from
>>>>>> www.unitemotor.com operated at =
>>>>>>>24Vdc. Motor specifications: 24Vdc, 2750 rpm,
>>>>>> 15.4amps, 280watts. There =
>>>>>>>is a 40 amp automotive fuse installed in-line 
on
>> the
>>>>>> each motor power =
>>>>>>>lead.  No other circuit protection is provided.
>>>>>>>
>>>>>>>    I have burned out three(3) Crydom D1D40 
SSR's
>>>>>> thus far.  This is =
>>>>>>>getting a little expensive for a hobby......
>>>>>>>
>>>>>>>    Can you help?
>>>>>>>
>>>>>>>    Circumstances of failures:
>>>>>>>
>>>>>>>    1.)Test #1; left SSR failed; left SSR -1
>>>>>> terminal wires became loose =
>>>>>>>during tank test run. Up to this time(20 
minutes
>> of
>>>>>> run time), the =
>>>>>>>electronics and drive system were operating 
with
>>>>>> full mixing and =
>>>>>>>proportional speed control.  Right drive motor
>> and
>>>>>> right SSR became very =
>>>>>>>hot.
>>>>>>>
>>>>>>>    2.)Test #2; right SSR failed after about 20
>>>>>> minutes of fully =
>>>>>>>proportional run-time. No apparent loose
>> electrical
>>>>>> connections. No =
>>>>>>>apparent mechanical binding in drive-train. 
Right
>>>>>> drive motor became =
>>>>>>>very hot.
>>>>>>>
>>>>>>>    Apparently, there are twenty to thirty RC
>> combat
>>>>>> tanks using the =
>>>>>>>same electronics(with Crydom SSR's) and drive
>>>>>> systems with almost =
>>>>>>>identical components with no problems.
>>>>>>>
>>>>>>>    Do you have any suggestions regarding the
>>>>>> inclusion of circuits or =
>>>>>>>components to protect the SSR's from being 
burned
>>>>>> out.  Could you please =
>>>>>>>be very specific with any suggestions regarding
>>>>>> protective circuits or =
>>>>>>>components(ie.-component/circuit installation
>> into
>>>>>> motor control wiring =
>>>>>>>and type and specific sizes of and sizes of any
>>>>>> components).=20
>>>>>>>
>>>>>>>
>>>>>>>    Thank you,
>>>>>>>
>>>>>>>
>>>>>>>    Grant P. Mahalek
>>>>>>>    gmahalek-at-shaw.ca
>>>>>>>    403-948-6443(res)
>>>>>>>    403-880-2070(bus, cell)
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>
>>
>> 
>
>