Re: which power contoller, choice of 3
- thanks guys
i was going for that one and was only put off by the power reading. i
can do the maths to work out the power like Mike says. but would
still prefer a reading (i would have to guess the heat loss for my
math, which is the main thing i want to know accurately, esp running
at low power).
the ammeter i use is a fluke 335 true RMS clamp meter. the spec sheet
says the range is 0-600A. crest factor(?) is 2.4@500A, 2.0@600A. AC
response is RMS. this sounds to me like the one Mike said with
the "integrating function built in". so i think i will be able to
measure the power after all. the other one is an old one with a
needle which is so old and slow it will probably not react fast
enough and will give an average power anyway!
i'll put my order in today for the burst type. i have all the heat
sink issue sorted too. it is sutronics which i think is the same as
Adrians so i'll give you a report on the linearity in a week or so.
--- In Distillers@y..., "Mike Nixon" <mike@s...> wrote:
> peter_vcb wrote:
> Subject: [Distillers] which power contoller, choice of 3
> i am getting my power controller this week (after being convinced
> Mike and Adrian!) and have three choices:
> check out this from radionics 308-584 says its "suitable for lamp
> dimming, heating controls etc." all it needs is a 220k or 250k
> potentiometer and can handle up to 15A. only 21 euro (25 including
> potentiometer) dont know if these links will work
> This is just a chip. Needs a filter, snubber, etc
> then there is 655-644 which is an "enclosed phase controlled
> regulator" again to 15A and is 41 euro.
> Needs a filter
> burst firing module 346-592 up to 13A costs 48.50 euro.
> Nice ... self-contained unit, specifically designed for resistive
> Details copied fron Radionics site are:
> A compact, epoxy resin potted, power controller for proportional
control of resistive loads from 1 to 3kW, 240V a.c. 50Hz
> Duty cycle adjustable from 0 to 100%
> Output circuit with zero voltage turn on/zero current turn off for
minimum RF interference
> Connection via 4 screw clamp terminals and 4BA earth stud on the
underside of the case
> Front panel fixing, nut and washer supplied
> Note : the thermal resistance of the panel/heatsink should be no
more than 2°C/W @ 35°C amb temp. (170x170x3mm aluminium panel).
Heatsink compound 554-311 is recommended.
> technical specification
> Max. cont. output current (Imax.) 13 A
> Max. single cycle surge 125 A
> Max. output current (1 sec.) 50 A
> Nom. r.m.s. input voltage (50 Hz) 240 V
> Max. peak repetitive voltage 600 V
> Forward voltage drop at Imax. 1·7 V
> Fusing I2t (t=10 ms) 110 A2s
> Operating temperature range -20°C to +70°C
> i now realise that a clamp type ammeter will not work with the
> firing module since it will be jumping up and down all the time (am
> right?) will an ammeter work with the phase controlled regulators.
> would be nice to know what power is going in watts rather than "1/4
> turn of a dial"
> which do you guys think would be best?
> Right ... a clamp type ammeter will not work unless it has an
integrating function built in to indicate mean current. These are
available, but cost more.
> If you are lucky, and they ARE right about that 0 to 100%
adjustment, then all you need do is mark off the dial from zero to
full power in equal increments. However, if you are uncertain, then
calibrating with just a watch and a thermometer is easy, and you only
have to do it once.
> Fill your boiler with 10 litres of water.
> Measure the temperature in deg C .... T1
> Set the controller to one of the marks on the dial and switch on
> Turn off power after 10 minutes and measure the temperature of the
water ... T2
> Temperature rise T = T2 - T1
> Power for that setting is 3T/43 kW
> Rather than try and change the marks on the control dial, it is
easier to make up a little chart which tells you the power level for
each dial setting, and then paste that on the cover of the controller.
> Mike N