Yokogawa Electric Corporation - TC10-L - ENGINEERING MANUAL - PAG. 12
6. OPERATIVE MODES
The TC10-L is an FM (both FM3545 and FM3810) approved
limit controller that can be confi gured either as a high limit or
as a low limit controller by a user.
The relay of the output 2 operates in fail-safe mode (relay
de-energized during shutdown condition) and latching mode.
OUT 2 turns OFF (in this document this condition will be
named shutdown) when:
The instrument is confi gured as a high limiter (Hi.Lo = Hi)
and the measured value is greater than limiter threshold
[“SP” parameter] or.
The instrument is confi gured as a low limiter (Hi.Lo = Lo)
and the measured value is lower than limiter threshold.
Out 2 remains OFF until the condition which generated the
shutdown, no longer exists and the Confi rming action (re-
arm) has been performed.
During a shutdown (Out 2 is OFF) the upper display will be
red.
Confi rming action (rearm) can be performed in two different
way:
- by pressing the
key [when “diS” parameter is set to
“but”] but it will be accepted only when the condition which
generated the shutdown, no longer exists (EX lamp is OFF)
and the set point is shown on the lower display (see “normal
display” in “Navigation access”)
- by momentarily closing the digital input (by an external dry
contact) [when diS parameter is set to “di”] but it will be ac-
cepted only when the condition which generated the shut-
down, no longer exists.
We defi ne also that the time duration of the shutdown condi-
tion, stored by the instrument, will be the time from Out 2
goes OFF (shutdown start) and the condition that generate
the shutdown no longer exists.
The confi rmation action is not part of this time count.
The time duration of the shutdown condition and max/min
measured values are stored in memory and available for
viewing (see “navigation access”) until the next shutdown
condition occurs.
These informations are lost at power down.
6.1 HIGH LIMIT CONTROL
PV
SP
Process Value
(in eng. units)
Set Point
(a)
(Editing mode)
Limit
Control
High
Limiter
Exceeded
indication
EX
OUT
PK
HI
AL1
AL2
TC10-L
Output
(b)
(c)
(d)
(e)
The HI lamp (d) is ON
When a measured value (a) is higher then the set point
(b),“EX” lamp (e) lights, “OUT” lamp (b) turns ON and the
limit output relay (Out 2) is de-energized.
EX lamp (e) turns off when PV goes into normal condition,
while the ”OUT” lamp (c) stays on as it is.
The out (c) lamp turns off only when the EX lamp (e) is off
and a confi rming operation (rearm) has been done by an
operator.
The way to confi rm are (according to the “diS” parameter):
- pressing
key for more than 3 seconds or
- by DI1.
Output relay is de-energized whenever “OUT” lamp is on.
Check the “HYS” parameter value if the EX lamp (e) is not
turn off when PV (a) is lower than SP (b).
SP
HYS
PV
(A)
(B)
(C)
(A)
(B)
(D)
EXCEEDED
LAMP
OUT
LAMP
lit
off
OUTPUT
RELAY
confirmation
(accepted)
confirmation
(not accepted)
lit
off
Energized
De-energized
OFF
OFF
OFF
Lit
Lit
OFF
Lit
ON
OFF
ON
OFF
Lit
OFF
When the EX lamp (e) is ON but PV (a) is lower than SP (b),
the upper display will be in green color and it shows that the
PV is in the hysteresis area
6.2 LOW LIMIT CONTROL
The HI lamp (d) is OFF
When a measured value (a) is lower than the set point (b),
“EX” lamp (e) lights, and “OUT” lamp (c) turns ON and the
limit output relay is de-energized.
“EX” (e) lamp turns off when PV goes into normal condition,
while the “OUT” lamp (c) lamp stays on as it is.
The out (c) lamp turns off only when the EX lamp (e) is off
and a confi rming operation (rearm) has been done by an
operator.
The way to confi rm are (according to the “dis” parameter):
- pressing
key for more than 3 seconds or
- by DI1.
The confi rming operation is not accepted during PV exceeds
SP (D) (during EXCEEDED lamp lights*). State of output
relay is de-energized whenever “OUT” lamp is on.
Output relay is de-energized whenever “OUT” lamp is on.
Check the “HYS” parameter value if the EX lamp (e) is not
turn off when PV (a) is lower than SP (b).
SP
HYS
PV
(A)
(B)
(C)
(A)
(B)
(D)
EXCEEDED
LAMP
OUT
LAMP
lit
off
OUTPUT
RELAY
confirmation
(accepted)
confirmation
(not accepted)
lit
off
Energized
De-energized
OFF
OFF
OFF
Lit
Lit
OFF
Lit
ON
OFF
ON
OFF
Lit
OFF
When the EX lamp (e) is ON but PV (a) is higher than SP
(b), the upper display will be in green color and it shows that
the PV is in the hysteresis area
