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

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

Good deal, sorry about that.  As Steve indicates you 
could put them across the output switching contacts 
of the SSRs but I don't think that's your problem.  
Just fyi, put the striped end (cathode) to the 
positive side and the other end (anode) to negative.  
A diode only pulls current one way.  If you get it 
backwards, you'll simply smoke the diode.  

If you simply get heat moved away from the SSRs I'm 
pretty sure you'd be fine.


--- Original Message ---
From: Grant Mahalek <gmahalek-at-shaw.ca>
To: tanks-at-rctankcombat.com
Subject: Re: D1D40 SSR's burning out??  Don't use a 
diode! [TANKS]

>Ted,
>
>Thanks for getting back to me so quickly about NOT 
using diodes....I was 
>just warming up the car to head out and buy some 
diodes.....No harm done!
>
>Regards,
>
>Grant
>
>
>----- Original Message ----- 
>From: "flier" <FLIER-at-sbcglobal.net>
>To: <tanks-at-rctankcombat.com>; 
<tanks-at-rctankcombat.com>
>Sent: Thursday, November 03, 2005 2:38 PM
>Subject: Re: D1D40 SSR's burning out?? Don't use a 
diode! [TANKS]
>
>
>> 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)
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>
>>
>> 
>
>