Schaffner Group
User and Installation Manual
Ecosine evo
October 2018
48/50
10 Trap circuit disconnect
The trap circuit disconnect feature is a modular option for the purpose of reducing the capacitive current
during low load operation, if needed. With permanently connected trap circuit, cos
φ
vs. load shows following
characteristics:
When the trap circuit is disconnected, cos(phi) returns to ~0.98. At the same time, the THID will increase.
This may be negligible, since absolute values are low due to reduced load power.
Needed external components (not part of ecosine filter) or system functions for fully automated capacitive
current control:
|
Motor load (power factor) monitoring device
|
Capacitor contactor
A reduced load system status may be available as system controller output signal. In this case, only adequate
driving of capacitor contactor has to be assured.
Note:
It is necessary to take into account overall concept of power factor correction. A system PFC correction
unit with large capacitor banks may become obsolete or massively reduced, when harmonic filters are
installed. In such cases it may not be necessary to install trap circuit disconnect functions.
Recommended settings:
Schaffner recommends to engage and disengage the trap circuit disconnect at following load levels:
Trap circuit status
Proposed load level
Disconnect
When load level drops under 10–15%
Connect
When load level rises above 20–25%
