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Thermal phase overload protection
(THOL)
For the alarm there is an output denoted ALARM which is active as long as the temper-
ature is above alarm level. For the tripping there are two outputs, one denoted TRIP
which gives only a 50 ms pulse at operation and one denoted START which is active as
long as the temperature is above the tripping level.
The simplified logic diagram for the THOL function is shown in figure 52.
1)
MI
Θ
IL1
THOL-BLOCK
TEST
TEST-ACTIVE
BlockTHOL = Y es
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The function is disabled (blocked) if:
•
The terminal is in TEST mode (TEST-ACTIVE is high) and the function has been
blocked from the HMI (BlockTHOL=Yes).
•
The input signal THOL--BLOCK is high.
The THOL--BLOCK blocking signal can be connected to a binary input of the terminal
in order to receive a block command from external devices or can be software connect-
ed to other internal functions of the terminal itself in order to receive a block command
from internal functions. Through an OR gate it can be connected to both binary inputs
and internal function outputs.
&
&
≥1
&
&KDSWHU
&XUUHQW
50 ms
THOL-TRIP
THOL-START
THOL-ALARM
1)
transducer input
en02000535.v sd
119
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