Chapter 3 - Device Overview
68 3BHS335648 E82 UNITROL 1020 User Manual
The dark-gray cells show the setpoint follow-up taken from the CAN Interface (more
reliable)
In order that the channel take over the previous operation point as fast as possible, the
PWM of the standby channel starts regulating with the same PWM value of the main
channel.
DCH Communication: Configuration and Compatibility
As explained in Chapter 3.4.4.4.3 DCH Monitor Functions
DCH communication must be enabled to use the Changeover feature. When the DCH
communication is enabled, measurement, setpoints and status indications from the
Second Channel are read and valid as long as the DCH Communication Status is logic
one; i.e. correctly configured, enabled and free of communication errors.
The Double Channel software is only partially compatible with the UN1000-PM40
module. The DCH Supervision can be used together with UN1000-PM40, because it
does not depend on the CAN communication status and activation. However, a PM40
module cannot be used in the same device, where Changeover and/or DCH Follow-up
features are also required. Even whenever DCH Communication can be enabled, the
operation of the UN1000-PM40 has a higher priority and the DCH data transmission will
be stopped as soon as the AVR detects a UN1000-PM40 on the CAN bus. This priority
order is fixed in the AVR and not configurable.
Even without functions from Redundant Channel support, a double channel system with
UN1000-PM40 can be built using analog and digital inputs and outputs as communication
interface between the AVRs. Furthermore, Alarm and Trip output signals from DCH
Supervision could be used to extend the functionality to some extent.
The AVR-ID should be configured with the same number in both channels. One channel
should be configured as Main and the other as Redundant. The channel identification can
be configured using the CMT1000 or Remote Access. Only one channel should be Active
while the other is in Standby. The use of interlocked contacts (connected externally) is a
recommended practice to assure this situation. The Standby/Active status of both
channels can be monitored using the CMT1000. For more information refer to Chapter
6.4 PC Software Tool.
3.4.4.5 Rotating Diode Monitoring (RDM)
The aim of the Diode Monitoring is to detect the following failures:
Break of a diode
Short circuit of a diode
It is needed in brushless excitation systems and can only be done indirectly, because the
diodes are part of the rotor. See the principle circuit for the excitation in Figure 3-16.
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