TR 03536 : 25A / 0,05 A and TR 03537 : 100 A / 0,2 A . During the
functioning it's possible to visualise on SV display the current measured by
TAHB input, expressed in Ampere (if obviously the TA ratio is 1/0,002)
pushing "LEFT" key. The alarm will be active when, in C1 output active
conditions, the current measured by TAHB input will results lower than the
value set on "ALHb" parameter. "ALHb" parameter has to be
programmed with the value of the current normally taken over by the load
driven by C1 output, considering as well the network tension fluctuations ,
in order to avoid undesired alarms. As regard the HB alarm hysteresis it's
automatically calculated by the instrument as 2% of "ALHb" and the
behaviour is the same as a minimum alarm. If it's desired to deactivate the
HB alarm, it's enough to program "ALHb" = 0.0.
It's possible to have 2
different HB alarm output behaviours, depending on the "rLHb" parameter
programmed.
"OPEn" = NORMALLY OPENED - The output is activated when the alarm
is active, while is deactivated when the alarm is not active.
"CLoS" = NORMALLY CLOSED - The output is activated when the alarm
is not active, while is deactivated when the alarm is active.
Notes :
In the connection of the Heater Break circuit it's necessary to
introduce a resistance of 10
Ω
(supplied with the instrument), connected in
parallel with the current transformer, on the instrument terminals, as
shown in drawing. The current measure through TAHB input needs at least
100 mS
.
4.13 - LOOP BREAK ALARM FUNCTION
In all instruments it's available an alarm that intervenes, automatically
turning the instrument into the OFF state, when, for any reason
(thermocouple short circuit, thermocouple inversion, load interruption) is
interrupted the regulation ring controlled by C1 output. To this alarm are
associated two parameters :
"LbAP"
- Value in percentage of C1 output power.
"LbAt" -
Maximum time at which the power, programmed on par. "LbAP",
can be applicable to the load (in sec.)
If C1 output power remains at an higher value than the value programmed
on par. "LbAP", for the time programmed on par. "LbAt", the instrument
will be turned into OFF state and on the display will appear the writing
"LbA OFF", flashing. Both parameters have to be carefully chosen in
order not to give rise to false alarms. To exclude the alarm, program
"LbAP" and "LbAt" = 0. To restore the functioning after the alarm,
reprogram the automatic control functioning (rEG).
4.14 - AUXILIARY DIGITAL INPUTS
As alternative to the serial line, the instrument can be equipped
with
optoisolated auxiliary inputs (AUXIN1 and AUXIN2), by means of which
it's possible to select one of the 4 predetermined set point, to change the
instrument functioning state or both things. The auxiliary inputs have to be
activated by devices without potential as contacts or open collector (NPN
transistor), considering that the COM terminal is the negative common
one. The functioning of the auxiliary inputs is defined by the parameter
"rEar"
, which can assume the following values :
"FF" = No function
"Fr" = Set point selection
"rF" = Control state selection
"rr" = Set point selection (SP1or SP2) through AUXIN1 and instrument
state selection (control or Off) through AUXIN2.
The following table indicates the programmable functions related to the
inputs state (considering the connected contacts state as opened = off or
closed = on) and to the programmed auxiliary inputs functioning mode:
SP2
OFF
Control
SP4
on
on
SP2
Control
OFF
SP3
on
off
SP1
OFF
-
SP2
off
on
SP1
Control
Man. Contr.
SP1
off
off
SPn
Control
State
Control
State
SPn
AUXIN2
AUXIN1
"rr"
"rF
"
"Fr
"
Whenever the digital inputs are used to establish the control mode ("rEAr"
= "rF") do program on parameter
"rEdF"
the control power, in case of
manual control.
4.15 - RS 485 SERIAL INTERFACE
The instrument can be equipped with an RS 485 serial communication
interface, by means of which it's possible to connect the regulator with a
net on which are connected other instruments (regulators or PLC) all
depending typically on a personal computer used as plant supervisor.
Through personal computer it's possible to acquire all the functioning
information and to program all the instrument configuration parameters.
The software protocol adopted for THP84 is the same of THP94 and is a
derivative from MODBUS RTU or JBUS protocol (AEG Schneider
Automation, Inc. Trade Mark) widely used in several PLC and supervision
programs available on the market (THP94 protocol manual is available on
request). The interface circuit is mounted with CMOS components that
presents weak pull up/down currents absorbed and therefore allows to
connect till 100 THP84 instruments on the same line. To maintain the line
on rest conditions it's required the connection with a 100 Ohm resistance
(Rt) at the end of the line. The instrument is equipped with two terminals
called A(L+) and B(L-) that have to be connected with all the namesake
terminals of the net. For the wiring operation it's enough then to interlace
a double cable (telephonic type) and to connect on ground all the GND
terminals. Anyway, particularly when the net results very long or noised
and being present potential differences between the GND terminals, it's
advisable to adopt a screened cable wired as in the drawing.
Adopting this electrical drawing and having care that the total capacity of
the line would not be higher than 200 nF, the total length of the line can
reach a maximum of 1500 meters. If the instrument is equipped with the
serial interface, the parameters to be programmed are the following :
"nStA"
: Address of the station. Set a different number for each station,
from 1 to 255.
"bAud"
: Transmission speed (baud-rate), from 300 to 9600 baud.
All the stations have to be the same transmission speed.
"PAcS"
: Programming access. If programmed as "LoCL" this means that
the instrument is programmable just from the keyboard, if programmed as
"LorE" it's programmable both from the keyboards and serial line.
When is tried to accede to programming from the keyboard while is having
place a communication through the serial door, the instrument visualise
"buSy"
to indicate the busy state.
5 - PROGRAMMING
In any state of control, pushing "P" key and keeping it pushed for about 3
seconds, is possible to accede to selection menu "SEL".
By means of "UP" key it's possible then to run over the selections :
"rEG"
: permits to turn the regulator into automatic control state
"OPEr"
: permits to get into the operative parameters menu
"ConF"
: permits to get into the configuration parameters menu
"SPn"
: permits to select the active Set point and appears only if par.
"nSP" is higher than 1
TECNOLOGIC - THP 84
USER MANUAL (I - GB) - Vr. 02 - ISTR 00132 - PAG. 17
