5.7 Alarm relay setpoint or trailing operation
Display: AxSP or Axt1 etc.
Range: AxSP or Axt1 etc.
Default Value: AxSP
Relay operation independent setpoint or trailing setpoint, this function only be seen where more
than one relay is fitted. Each alarm relay, except relay 1, may be programmed to operate with
an independent setpoint value or may be linked to operate at a fixed difference to another relay
setpoint, known as trailing operation. The operation is as follows:
Alarm 1 (AI) is always independent. Alarm 2 (A2) may be independent or may be linked to
Alarm 1. Alarm 3 (A3) may be independent or may be linked to Alarm 1 or Alarm 2. Alarm 4
(A4) may be independent or may be linked to Alarm 1, Alarm 2 or Alarm 3. The operation of
each alarm is selectable by selecting, for example, (Alarm 4) A4.SP = Alarm 4 normal setpoint
or A4.t1 = Alarm 4 trailing Alarm 1 or A4.t2 = Alarm 4 trailing Alarm 2 or A4.t3 = Alarm
4 trailing Alarm 3. For trailing set points the setpoint value is entered as the difference from the
setpoint being trailed. If the trailing setpoint is to operate ahead of the prime setpoint then the
value is entered as a positive number and if operating behind the prime setpoint then the value is
entered as a negative number.
Example: With Alarm 2 set to trail alarm 1, if A1Hi is set to 1000 and A2Hi is set to 50
then Alarm 1 will activate at 1000 and alarm 2 will activate at 1050 (i.e. 1000 + 50). If Alarm
2 had been set at -50 then alarm 2 would activate at 950 (i.e. 1000 – 50).
5.8 Alarm relay operation mode e.g. A1 OPER etc.
Display: Ax OPEr
Range: Ax.AL or Ax.tP or Ax.Fr
Default Value: Ax.AL
Alarm relay operating mode (relays 1 and 2 only) - this function allows selection of standard alarm
on/off setpoint operation (A1.AL or A2.AL) using the alarm functions described in this chapter
or PI control operation (A1.tP or A1.fr or A2.tp or A2.fr). To set the alarm operation mode
go to the Ax OPEr function and use the ^ or v push buttons to choose the required operation
then press F to accept this value.
Refer to the “Setting up the relay PI controller” chapter 7 for details of the PI control operations
and functions. Example:
With Ax OPEr set to A1.fr relay 1 will operate as a PI control relay with the frequency of the
relay varying.
5.9 Display brightness
Display: brGt
Range: 1 to 15
Default Value: 15
Displays and sets the digital display brightness. The display brightness is selectable from 1 to 15,
where 1 = lowest intensity and 15 = highest intensity. This function is useful for improving the
display readability in dark areas or to reduce the power consumption of the instrument. See also
PM4IVMAN-2.4-0 21 of 56
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