µRack
Cod. CAREL +03P220431 rel. 0.0 del 08/09/05 - preliminary version
7
3.2.1. Input configuration
Inputs from 1 to 4 are alarm inputs for the compressors and fans configured. If 5 devices are controlled by the unit, input no. 5 is automatically an alarm input (fan
alarm only).
The user can decide whether the alarm inputs are normally closed (the alarm condition exists when the contact is open) or normally open (the alarm condition
exists when the contact is closed) by setting parameter /14.
If 4 devices are connected to the controller, input 5 automatically becomes a multifunction input.
Parameter /15 can be used to configure the multifunction input:
• 0: no function
• 1: unit ON-OFF (ON contact NC)
• 2: change set point (set1- set2)
• 3: general high pressure switch NC
• 4: general high pressure switch 1 NO
• 5: general low pressure switch circuit 1 NC
• 6: general low pressure switch circuit 1 NO
• 7: general low pressure switch circuit 2 NC
• 8: general low pressure switch circuit 2NA
• 9: liquid level alarm NC
• 10: liquid level alarm NO
• 11: fan thermal overload/generic NC
• 12: fan thermal overload/generic NO
3.2.2. Unit ON/OFF
The controller is normally configured as always ON.
The unit can be switched on and off by:
1. Alarm (parameter A22 can be used to select whether or not a broken probe alarm should switch the unit off).
2. Supervisor (parameter /38 can be used to enable unit shutdown from the supervisor).
3. Digital input (parameter /15 can be used to configure the multifunction input as ON/OFF).
4. Parameter (parameter /39 can be used to switch the unit on or off)
Shutting down the unit, as shown on the display by the message “OFF”:
• switches the controller off
• stops the management of the various devices and the related alarms.
3.3. Meaning of the inputs / outputs
3.3.1. Table of analogue inputs
The tables below describe the type of the probes that can be connected to the inputs and their characteristics.
Analogue inputs
Input Description Type of probes that can be connected
B1 Ratiometric discharge pressure probe RATIOMETRIC pressure probe (0 to 5 Volt)
B2 Room temperature probe (display) / auxiliary probe CAREL NTC temperature probe (-50T100°C; R/T 10 kΩ at 25°C)
B3
Outside air temperature probe (floating condenser control) /
auxiliary probe
CAREL NTC temperature probe (-50T100°C; R/T 10 kΩ at 25°C)
B4 Ratiometric suction pressure probe / probe in 2nd circuit RATIOMETRIC pressure probe (0 to 5 Volt)
Table3.1
Digital inputs
Input Description Type of device connected
ID1 Compressor 1 / fan alarm Generic compressor/fan alarm. Voltage-free contact.
ID2 Compressor 2 / fan alarm Generic compressor/fan alarm. Voltage-free contact.
ID3 Compressor 3 / fan alarm Generic compressor/fan alarm. Voltage-free contact.
ID4 Compressor 4 / fan alarm Generic compressor/fan alarm. Voltage-free contact.
ID5 Fan alarm / Multifunction input Generic alarm:
- compressor/fan.
- from general high/low pressure switch.
- fan thermal overload.
- liquid level.
Unit On-Off. Voltage-free contact.
Digital outputs
Input Description Type of device connected
No1-C1 Compressor 1 / fan Power contactor for starting the compressor / fan
No2-C2 Compressor 2 / fan Power contactor for starting the compressor / fan
No3-C3 Compressor 3 / fan Power contactor for starting the compressor / fan
No4-C4 Compressor 4 / fan Power contactor for starting the compressor / fan
No5-C5 Alarm / fan Power contactor for starting the fan / voltage-free contact for signalling unit alarm
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