Nidec Kato Engineering KRM2000 - Feature Description; Functional Block Diagram; Theory of Operation

26 | Kato Engineering, Inc.
5 Feature Description
This section will describe all of the functional features and parameters provided with the KRM2000
TM
system. All programmable features are done through the KRM2000
TM
receiver.
5.1 Functional Block Diagram
The KRM2000
TM
provides flexibility in communications, allowing for the user to collect data and make
settings adjustments through many different protocols. The stationary receiver contains a DSP that
does all of the conversion of data that was collected over the air from the rotating transmitter.
DSP
EEPROM
+12V
SWITCHER
+5V
SWITCHER
3.3V LDO
1.9V LDO
-3.3V
REF
24V DC
POWER
SUPPLY
TRANSCEIVER
TRANSMITTER
POWER
AMP
STATIONARY
RECEIVER
ROTATING
TRANSMITTER
INDUCTIVE
LOOP
ANTENNA
POWER
CONVERTER
MICROCONTROLLER
ANYBUS
PORT B
ANYBUS
PORT A
GROUND FAULT
MONITORING
CIRCUITS
EXCITER
ARMATURE
GENERATOR
FIELD
BRUSHLESS
EXCITER ROTOR
DIODE FAULT
MONITOR
ISOLATOR
JTAG
INTERFACE
USB
PORT
SIGNAL
DRIVERS
MALFUNCTION
GROUND FAULT
DIODE FAULT
RELAY
DRIVERS
SERVICE FAULT
GROUND FAULT
MALFUNCTION
90-240VAC
POWER IN
Figure 21 KRM2000
TM
Functional Block Diagram
5.2 Theory of Operation
The rotating transmitter module contains circuitry capable of detecting the occurrence of a
generator ground fault condition. In this case the ground fault condition is defined as an electrical
leakage path modeled as a resistance that may exist from any point along the field winding to the
rotor shaft (ground). An effective ground fault detector must respond to ground faults at any
location on the field winding. The ground fault detection circuitry makes an electrical connection
between the rotor ground and the generator field introducing a small DC voltage that floats the field
above ground. The transmitter monitoring circuits sense leakage currents to ground by using a
pulsed DC bias voltage method. Using this method, the transmitter detector determines the actual
field leakage resistance to ground and not just the leakage current. The leakage current to ground
is dependent not only on the value of field leakage resistance to ground, but also on the magnitude