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5.2.2 Single phase contact output (oP1-8)
Phase-shifting output is usually realised by TRIAC.but it will has influence on heater, so please make sure of
the anti-interference of other equipments when use it.
5.2.3 SV limit setting (only for AI-518,and CF.C=0)
SV is usually between HIAL and LoAL. So that to make sure SV is not too high nor too low. If no auto-alarm
is installed, it maybe burnt, in order to cancel it, you can set CF.C=1. AI-518P programmable given SV is not
limited.
5.2.4 Alarm blocking at the beginning of power on(CF.B=1).
Some unnecessary alarms often occur at the beginning of power on or when the setpoint is modified.
For example, in a heating system, at the beginning of powers on, its temperature is much lower than the
setpoint. If low limit and deviation low limit are set and the alarm condition are satisfied, the instrument
should alarm, but there is no problem in the system. Contrarily, in an refrigerating system, the unnecessary
high limit or deviation high limit alarm may occur at the beginning of power on. Therefore, AI instruments
offer the function of alarm blocking at the beginning of power on. Alarm blocking function is correlative to
direct/reverse action control. In a reverse action control system (refer to CF), the corresponding absolute
and deviation low limit alarms are blocked until the alarm condition first clears. If the alarm condition is
satisfied again, the alarm will work. Similarly, in a direct action control system, the absolute and deviation
high limit alarms are blocked.
5.2.5 Sectional power restriction(CF.E=1).
With regards to some high temperature electric resistance furnace whose heating materials is
silicon-molybdenum bar or tungsten filament, the resistance of there heater in cold condition is much lower
than that in hot condition, so the furnace current will exceed its rated current greatly in cold condition. If the
instrument works in automatic control mode, full power output in cold condition will lead to power switch trip
and shorten the heating materials service life to a large extent.
The function of sectional power restriction will be executed if CF.E=1. Then the instrument output lower
limit will be fixed on 0, while oPL is the output upper limit when the temperature is lower than the value of
lower limit alarm. If the temperature is higher than the lower limit alarm value, oPH is the upper limit of
output. In this way, the instrument can work with 2 optional power according to the measurement in order to
restrict the oversized current in cold condition. Lower limit alarm function will be canceled when sectional
power restriction function is active.
For example: If it is needed that output power should be restricted to 20% when the furnace temperature
is lower than 600
℃
and 100% when the temperature is higher than 600
℃
. Parameters is as follows:
LoAL=600, oPL=20, oPH=100, CF.E=1 (see parameter CF for details).
5.2.6 Dual given value switch/ external programmable control button
