16
PKE-COM-RTU Modbus RTU communication interface for PKE12/32/65
03/20 MN034005EN
The test position on the PKE trip block and remote tripping through output bit
R-TRIP cause a trip when a phase current of at least 85 % of the minimum mark
of the variable overload release on the PKE trip block flows through all three main
circuits (for example PKE-XTUA-4
Imin = 0.85 × 1 A = 0.85 A).
2.7.5 Relative current value (I-REL)
The PKE motor protection switch provides the current motor current via register 30009
2. The motor current is shown as a relative value in the ranges 0 % (0x00) to 120 %
(0x78). The transferred relative value is calculated from the value of the highest phase
current measured in relation to the set current value of the overload release. The PKE
circuit breaker provides the actual phase currents L1, L2, L3 via registers 30010 - 30012.
It will be represented as a relative value within a range of 0 % (0x00) to 120 % (0x78).
The transferred relative value refers to the set current value of the overload release.
The accuracy of the relative current indication depends on the measured phase current
in relation to the current range of the PKE trip block. In order to measure the phase
current with sufficient accuracy, a phase current of at least 85 % of the minimum mark
of the variable overload release on the PKE trip block (e.g. trip block PKE-XTUA-4
Imin = 0.85 x 1 A = 0.85 A) must be present.
The maximum measuring accuracy of the transferred relative current value is 5 %.
2.7.6 Thermal motor image (TH)
Depending on the current range and the actual current flow, the PKE motor-protective
circuit-breaker calculates the thermal state of the motor and provides it as a data byte.
The thermal load of the motor is mapped via register 30006. It will be represented as
a relative value within a range of 0 % (0x00) to 120 % (0x78).
The main circuits are interrupted as a result of a motor overload if the thermal motor
image is 110 %. In the event of phase failure or phase unbalance, the main circuits are
interrupted at a value of 100 % of the thermal motor image. In the event of a phase
unbalance and trip caused by an overload, the value of the thermal motor image is
raised from 100 % to 110 %.
2.7.7 Type of trip block (TYPE)
The modular system of the PKE electronic motor protection switch enables several
different current ranges to be covered. A different PKE trip block is inserted into the PKE
basic device depending on the current range required. The following PKE trip blocks of
the type "Extended" can be combined with the PKE basic devices PKE12, PKE32
and PKE65.
Table 6: Combination options for the PKE basic device with the PKE trip block
The type of PKE trip block is mapped via the bit field TYPE register 30001. The values of this bit field
are assigned to the following PKE trip blocks:
Basic
device
PKE-
XTUA-1.2
PKE-
XTUA-4
PKE-
XTUA-12
PKE-
XTUA-32
PKE-
XTUWA-32
PKE-
XTUACP-36
PKE-
XTUWACP-36
PKE-
XTUA-65
PKE12
✓
✓
✓
X
X
X
X
X
PKE32
X
X
✓
✓
X
✓
X
X
PKE64
X
X
X
X
✓
X
✓
✓
2.7 Programming
2 Modbus RTU