6 POLE DEAD FUNCTION
The Pole Dead Logic is used to determine and indicate that one or more phases of the line are not energised. A
P
ole Dead condition is determined either by measuring:
● the line currents and/or voltages, or
● by monitoring the status of the circuit breaker auxiliary contacts, as shown by dedicated DDB signals.
It can also be used to block operation of underfrequency and undervoltage elements where applicable.
6.1 POLE DEAD FUNCTION IMPLEMENTATION
Pole Dead logic can be implemented in all of the P64x models. If implemented in the P642, it requires a model with
tw
o single phase VT inputs. If implemented in the P643 or P645, it requires a three phase VT input.
In the P642, the phase -to-phase voltages VAB and VBC are considered, whilst in the P643 and P645, the phase -to-
neutral votlages VAN, VBN and VCN are considered.
The pole dead function is used to determine when the circuit breaker poles are open. This indication may be
forced, using status indication from CB auxiliary contacts (52a or 52b) mapped to opto-inputs, or internally
determined by the device. If internally determined, the 52b contacts are used and inverted in the PSL because only
the CBx closed DDB signal is available for each breaker. The device will also initiate a pole dead condition for the
following conditions:
● VTS Slow Block DDB signal is low,
● The line current and voltage fall below a preset threshold.
This is necessary so that a pole dead indication is still given even when an upstream breaker is opened. The
undervoltage and undercurrent thresholds have the following, fixed, pick-up and drop-off levels:
● VA<, VB<, VC<, these level detectors operate on phase voltages and have a fixed setting, Pick-up level = 10 V
(Vn = 100/120 V), 40 V (Vn = 380/480 V), Drop Off level = 30 V (Vn = 100/120 V), 120V (Vn = 380/480 V).
● VAB<, VBC<, these level detectors operate on phase-phase voltages and have a fixed setting, Pick-up level =
70 V (Vn = 100/120 V), Drop Off level = 95 V (Vn = 100/120 V).
● IA<, IB<, IC<, these level operate on phase currents and have a fixed setting, Pick-up level = 0.05 In, Drop Off
level = 0.055 In.
Note:
f the VT is connected at the busbar side, auxiliary contacts (52a or 52b) must be connected to the device for a correct pole
dead indication.
Chapter 13 - Monitoring and Control P64x
278 P64x-TM-EN-1.3
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