Vaisala BAROCAP PTB330 Guide de l'utilisateur télécharger pdf (Page 97)

Chapter 4 ________________________________________________________________ Operation

VAISALA _______________________________________________________________________ 95

Hysteresis

The hysteresis function prevents the relay switching back and forth

when the measured value is near to the setpoint values. The relay is

activated when the measured value passes the exact value of the

setpoint. When returning to and passing through the setpoint again, the

relay is not released before the value reaches the setpoint

increased/decreased by the hysteresis value, see Figure 39 on page 94.

The hysteresis should be sm

aller than the difference of the setpoints.

NOTE

If both setpoints are specified and the "above" setpoint is lower than

the "below" setpoint, the hysteresis works in the opposite direction,

that is, the relay is released when the measured value passes the exact

value of the setpoint.

Relay Indicating Barometer Error

Status

You can set a relay to follow the operation status of the device. By

selecting FAULT STATUS for output quantity a relay changes state

on the basis of the operation status as follows:

FAULT STATUS

Normal operation: relay active (C and NO outputs are closed)

Not measuring state (error state): relay released (C and NC outputs are

closed).

See Figure 40 below for an illustrative example of the FAULT

STATUS relay output mode.

1212-004

Figure 40 FAULT STATUS Relay Output Mode

1 2 ... 92 93 94 95 96 97 98 99 100 101 102 ... 143 144

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Vaisala BAROCAP PTB330 Guide de l'utilisateur Page 97