Azbil DCP31 - Page 168

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Chapter 7. PARAMETER SETUP
[Resistor type]
WhendrivinganSSRbyvoltagetime-proportionaloutput,theout-
putvoltageofthecontrollermustbewithintheinputratedvoltage
(optimumignitionvoltage)oftheSSR.
OntheDCP31,anewlydevelopedvariableoutputsystemisutilized
thatenablesoutputoftheoptimumignitionvoltageevenwhendriv-
ingtwoormoreSSRs.
Thissystemsetstheoptimumcurrentvalueonthecontrollersothat
theoptimumignitionvoltagewithrespecttotheinternalimped-
anceoftheSSRsidecanbeobtained.
Thefollowingshowsequivalentcircuitsandrelatedformulas:
•DescriptionofSymbols
(1) Details
I
O
 :Settingoutputcurrentofcontroller(settingrange:2
to22mA)
V
O
 :Maximumappliedloadvoltage(approx.14.7V)
V
SSR’
 :ActualinputvoltagetoSSR
V
SSR
 :InputratedvoltagerangeofSSR(V
SSR/MIN
to
V
SSR/MAX
)
V
SSR/MIN
 :MinimuminputratedvoltageofSSR
V
SSR/MAX
 :MaximuminputratedvoltageofSSR
  Z :InternalimpedanceofSSR
V
D
 :InternalvoltagedropofSSR(normally1to2V)
(2)EquivalentcircuitwhenoneSSRisconnected
  Formulas(1)and(2)formulasmustbesatisfied.
  (1)formula V
SSR/MIN
≤I
O
×Z+V
D
≤V
O
  (2)formula V
SSR'
<V
SSR/MAX

(V
SSR'
=I
O
×Z+V
D
)
DCP31 SSR
+
–
+
–
I
O
(V
O
)
V
SSR'
Z
V
D