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This type of alarm depends on use of the current transformer (C.T.) input.
It can signal variations in load input by identifying the current value in ammeter input in the range (0 ... HS.2). It is enabled by
means of configuration code (AL.n); in this case, the alarm trip value is expressed in HB scale points.
By means of code Hb.F (“Out” phase), select the type of functioning and the assigned control output.
The alarm limit setting is A.Hb.
The direct HB alarm trips when the ammeter input value is below the limit set for Hb.t seconds of the "ON" time for the selected
output.
The HB alarm can be activated only with ON times greater than 0.4 seconds (excludes continuous output).
The HB alarm also checks load current during the OFF interval of the cycle time for the selected output. The HB alarm trips if
the measured current exceeds approximately 12.5% of the full scale set for HB.t seconds of OFF status of the output
(parameter HS.2 in InP).
The alarm is reset automatically if its cause is eliminated.
Setting limit A.Hb = 0 disables both types of HB alarms, with de-energizing of the assigned relay.
You can display the load current by selecting the item In.2. (level 1).
NOTE: ON/OFF times refer to the cycle time set for the selected output.
Continuous alarm Hb_F = 3 (7) is active for a load current value below the set limit. It is disabled if the heating (cooling) output
value is below 3%.
The input value and alarms are frozen while the logic input is closed.
With logic input closed, a reset turns OFF both the relay outputs and the alarms latch.
HB ALARM FUNCTION
• HOLD function
29
7 • ALARMS
time
AL1 + Hyst1
AL2 + Hyst2
AL2
AL1
alarm 1
alarm 2
(*)
For AL1 = reverse absolute alarm (low) with positive Hyst1, AL1 t = 1
(*) = OFF if disabled on power-up
For AL2 = direct absolute alarm (high) with negative Hyst2, AL2 t = 0
For AL1 = symmetrical Lo absolute alarm with Hyst1, AL1 t = 5
For AL1 = symmetrical Hi absolute alarm with Hyst1, AL1 t = 4
* Minimum hysteresis = 2 scale points
Normal absolute alarm
Symmetrical absolute alarm
reverse alarm
direct alarm
AL1
AL1 + [ Hyst1 * ]
AL1 - [ Hyst1* ]
time
For AL1 = Lo deviation alarm with negative Hyst 1, AL1 t = 3
For AL1 = Hi deviation alarm with negative Hyst 1, AL1 t = 2
For AL1 = Symmetrical Lo deviation alarm with Hyst 1, AL1 t = 7
For AL1 = Symmetrical Hi deviation alarm with Hyst 1, AL1 t = 6
time
SP+AL1
SP
reverse alarm
direct alarm
SP+AL1
SP
reverse
alarm
direct
alarm
time
Hyst1
Deviation alarm
Symmetrical deviation Alarm
SP-AL1