Thermo Fisher Scientific Alpha DO 2000 - Manual (Page 52)

Instruction manual
Alpha DO 2000
Control signal of pulse length controllers
Relay
ON
tON tOFF
Pulse Length T
OFF
Time [s]
The output relay of the pulse length controller is clock-timed. The switching period T
remains constant. Depending on the divergence from the limit value, the switch on
time tON is increased or decreased in accordance with the proportional range Xp.
The following applies:
tON + tOFF = T (Const.)
greater divergence
Î greater tON
Xp exceeded Î tON = T (relay remains picked up)
Control signal of Pulse Frequency Controllers
Relay
ON
tON tOFF
Pulse Length T
OFF
Time [s]
The output relay of the pulse frequency controller is clock-timed. The pulse duration
tON remains constant at 250 msec. Depending on the divergence from the limit
value, the frequency (1/T) is increased or decreased in accordance with the
proportional range Xp.
The following applies:
tON = Const. (250 msec.)
greater divergence Î greater f (greater frequency)
Xp exceeded Î max. frequency
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