14
AGL_Unit_LOCU_EN_Rev00
Figure 14: XCM25D controller functionality overview
2.10.3 Modbus Communication
The XCM25D controller can communicate via Modbus (RS-485) connection to provide all running
data. Additional commands can also be activated through Modbus connection. The Modbus map is
available on request from the Application Engineering department at Emerson.
A pre-configured X-Web Supervisor device is also available and allows easy handling and
connectivity with the XCM25D controller.
Figure 15: Modbus port and termination jumpers
NOTE: If the XCM25D controller is connected in chain the termination jumpers must be
removed.
2.10.4 Main control & safety features
Suction pressure control:
Each unit is equipped with a suction pressure transmitter. The XCM25D
controls the suction pressure by evaluating the input signal of the pressure transmitter. The suction
pressure regulation f or LOCU units must be def ined by the setpoint (
C16
) and proportional band
(
C17
). The signal of the suction pressure transmitter is also used for additional functionalities.
Condensing pressure control:
Each unit is equipped with a high-pressure transmitter. The
XCM25D controls the condensing pressure by regulating the f an speed corresponding to the ambient
temperature. The unit controller regulates the condensing pressure with a constant temperature
dif ference to the ambient ("floating HP"; factory setting
E66
= 8 K).
Dif ferent control options are available. As soon as f an modulation is enabled (E01 = "2-Modulated
f an") parameter
E38
allows to choose "f loating HP" (f actory setting) or control of condensing
temperature inside compressor envelope. In this mode, the compressor can run different minimum
condensing temperatures based on the suction pressure of the compressor. This is the most energy-
ef f icient way to minimize the condensing temperature as much as possible. However it also means
that the f an is running at full speed more often than in floating HP mode.
Automatic liquid injection on OLE & OLTE models:
A mechanical injection valve (LIV) allows
liquid ref rigerant to be injected into the scroll set of the compressor to reduce discharge temperatures
generated when the unit operates at increasing compression ratios. There is a bulb on each
Condenser fan
control
Digital scroll
control
Superheat control
Liquid injection
Alarm
management
Electrical
protection
Monitoring of the discharge
line temperature
Содержание Copeland OLE-49
Страница 5: ......