Vemer FHT Series User Manual page 9

If both outputs are used, the hysteresis of each output is equal to half of the
differential. In this case output 1 will turn on when the parameter measured reaches
the value [ST1]-[DF1]/2; output 2 will turn off on reaching this value.
Dead-band operation mode [PRO=2]
• When in this mode output 1 operates in reverse and output 2 in direct.
It is necessary to confi gure parameters set-point 1 [ST1], differential 1 [DF1] and
dead band [DBN], which typify both outputs.
The regulator will tend to keep the parameter within the dead band. Outside the dead
band output 2 will turn on if the parameter tends to increase; conversely output 1
will turn on if the parameter tends to decrease. If only one output is present, it will
operate in reverse, with the hysteresis to the left of the value [DBN].
ON
OFF
PWM operating mode [PRO=5]
• The regulation logic of this operating mode is the same as that of the dead band
operating mode.
It is therefore necessary to confi gure parameters set-point 1 [ST1], differential 1
[DF1] and dead band [DBN], which typify both outputs. When in this operating mode,
relays are activated by impulses with the timing given by value [TCL] (see output
menu).
During that period the relay remains on for a variable length of time that is
proportionate to parameter deviation from the set-point (considering the dead band
when present). Beyond the differential value, the relay remains active 100% of the
time.
ON
OFF
Mode PRO=2
OUT 1
ON
R
ZN
OFF
Diff. 1
Set 1
1 output
Mode PRO=5
OUT 1
ON
ZN
R
OFF
Diff. 1
Set 1
1 output
User Manual – Thermoregulator FHT
OUT 1
R
ZN ZN
Diff. 1
Set 1
2 outputs
OUT 1
ZN ZN
R
Diff. 1
Set 1
2 outputs
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OUT 2
D
Diff. 1
OUT 2
D
Diff. 1