Relief Devices; Variable Frequency Drives - Carrier AquaForce B Series Controls, Start-Up, Operation, Service And Troubleshooting Instructions

OIL SEPARATOR HEATERS
Each oil separator circuit has a heater mounted on the side of
the vessel. Oil heater operation uses the following criteria:
1. The circuit's Oil Heater (Oil Heater Output A or Oil Heat-
er Output B) will be ON if the circuit's compressor status
(Compressor A or Compressor B) is OFF and the Oil
Level Switch (Oil Level Input A or Oil Level Input B) is
CLOSED.
2. The circuit's Oil Heater (Oil Heater Output A or Oil Heater
Output B) will be ON if the OAT is less than 99°F (37.2°C)
and either of the following conditions is true:
a. The OAT minus the circuit's SST (SST A or SST B) is
less than 30°F (16.6°C) and the circuit's Discharge
Pressure Temperature (Discharge Pressure A or Dis-
charge Pressure B) is less than 203 psig (1400 kPa).
b. The OAT minus the LWT is less than 30°F (16.6°C)
and the circuit's Discharge Pressure Temperature
(Discharge Pressure A or Discharge Pressure B) is
less than 203 psig (1400 kPa).
3. The circuit's Oil Heater (Oil Heater Output A or Oil Heater
Output B) will be OFF if the OAT is less than 99°F (37.2°C)
and either of the following conditions is true:
a. The OAT minus the circuit's SST (SST A or SST B) is
less than 30°F (16.6°C) and the circuit's Discharge
Pressure Temperature (Discharge Pressure A or Dis-
charge Pressure B) is less than 275.5 psig (1900 kPa).
b. The OAT minus the LWT is less than 30°F (16.6°C)
and the circuit's Discharge Pressure Temperature
(Discharge Pressure A or Discharge Pressure B) is
less than 275.5 psig (1900 kPa).
4. The circuit's Oil Heater (Oil Heater Output A or Oil Heater
Output B) will be OFF if the OAT is greater than 100°F
(37.8°C) and either of the following conditions is true:
a. The OAT minus the circuit's Saturated Suction Tem-
perature (Saturated Suction Temp A or Saturated Suc-
tion Temp B) is greater than 32°F (17.7°C).
b. The OAT minus the LWT is less than 32°F (17.7°C).

Relief Devices

Fusible plugs are located in each circuit between the condenser
and the liquid line shutoff valve.
PRESSURE RELIEF VALVES
Valves are installed in each circuit and are located on the evap-
orators and oil separators. These valves are designed to relieve
if an abnormal pressure condition arises. Relief valves on all
evaporators relieve at 220 psig (1517 kPa). Relief valves on oil
separators relieve at 350 psig (2413 kPa). These valves should
not be capped. If a valve relieves, it should be replaced. If the
valve is not replaced, it may relieve at a lower pressure, or leak
due to trapped dirt from the system which may prevent reseal-
ing. See Table 47. Some local building codes require that re-
lieved gases be exhausted to a specific location. This connec-
tion allows conformance to this requirement.
Table 47 — Relief Valve Connection Specifications
LOCATION
Oil Separator
Evaporator
CONNECTION SIZES
3/8 SAE Flare
3/4 in. NPT Female
Inspection and Maintenance
The relief valves on this chiller protect the system against the
potentially dangerous effects of overpressure. To ensure
against damage to the equipment and possible injury to person-
nel, these devices must be kept in peak operating condition. As
a minimum, the following maintenance is required:
1. At least once a year, disconnect the vent piping at the valve
outlet if equipped. Inspect the vent piping for corrosion, a
restriction or blockage. If any is found, clean or replace the
affected vent piping.
2. Carefully inspect the valve body and mechanism for any evi-
dence of internal corrosion or rust, dirt, scale, leakage, etc. If
corrosion or foreign material is found, do not attempt to re-
pair or recondition; replace the valve.
3. If the chiller is installed in a corrosive atmosphere or the
relief valves are vented into a corrosive atmosphere, in-
spect relief valves and piping at more frequent intervals.

Variable Frequency Drives

The 30XV units with Greenspeed
with VFDs to control the compressors and condenser fans. The
Danfoss VLT 1 HVAC drives each include an LCD user inter-
face display. However, all necessary functions and statuses can
be accessed from within the Carrier Controller menus. The
VFDs are configured through the Carrier Controller controls,
and parameters should not be changed manually.
ADDRESSING
The 30XV units with Greenspeed Intelligence use Danfoss
VFDs that operate by communicating commands to the drive.
As a result, each drive must have a unique address as shown in
Table 48. Addresses must be set in VFD Parameter 8-31.
Table 48 — VFD Addresses
VFD
Compressor A
Compressor B
Circuit A Fan Drive 1
Circuit A Fan Drive 2
Circuit B Fan Drive 1
Circuit B Fan Drive 2
COMMUNICATION
The 30XV units use Danfoss VFDs that operate by communi-
cating commands to the drive over the LEN bus. As a result,
each drive must have a unique address.
COMMUNICATION WIRING
LEN wiring is connected to each drive at VFD Terminals 61
(Ground), 68 (+) and 69 (-). See Fig. 73.
VFDs should be arranged in a daisy-chain pattern, meaning the
communication wiring is connected to one drive, exits and is
connected to the next. This pattern repeats until the last drive
on the communication bus is reached. See Table 49 to deter-
mine correct Communications Wiring in Fig. 75-79.
1. VLT is a registered trademark of Danfoss Group Global.
76
® Intelligence are equipped
Address
181
182
184
185
187
188