NHP TemBreak PRO, User Manual

Page: 37 / 105

Alarms & Indication
37
TemBreak PRO
B_BE-UM-001-EN
– V1.1.0
PTA (Pre-Trip Alarm)
The Pre-Trip Alarm permits monitoring and early warning of overload conditions prior to an actual LTD trip. The PTA setting is defined by two parameters
which define the Pre-trip warning and Pre-trip Alarm zones and thus the behaviour of the PTA contact and status LED:
-
PTA current threshold I
p
: Threshold expressed as a percentage of I
r
and is fixed at 80% x I
r
.
-
PTA time delay t
p
: Expressed as a percentage of t
r
and is fixed at 40 seconds.
The I
p
current threshold defines the lowest current that could be considered to be within the Pre-trip alarm zone. The t
p
time delay threshold defines the
shortest time in which the Pre-trip alarm will activate.
If the load current is less than the I
p
current threshold, then this is considered the normal load zone. The PICK UP LED and PTA contact are unaffected and
remain OFF and OPEN, respectively.
As the load current increases to at or above I
p
, the Pre-trip warning zone is entered, and is indicated by the PICK UP LED illuminating FLASHING red.
Pre-trip zone Current I vs I
p
LED status PTA contact status
Normal Load
I < I
p
(0.8xI
r
)
OFF
OPEN
Pre-trip Alarm
I ≥ I
p
(0.8xI
r
)
FLASHING
CLOSED
Power supply requirement
Operation of the PTA option requires an external OCR control power supply, which is mounted either locally on the side of the MCCB (all models), or
remotely on special request (all models excluding B250).
OCR power supply specifications Attribute
Voltage 200…240 Vac
Rated power 2 VA