Page 61 of 108
M-AP-001-EN Rev. N
System Design Guidelines
13.4 Electrical
Requirements
13.5 Application-Specific
Requirements
13.5.1 Medium
Evaporating Temperature
Application (TT300)
Power is permanently connected to the compressor connection terminals. A line reactor
must be connected in series with the compressor connection. The line reactor enclosure or
box should be properly ventilated to avoid overheating.
1. Check the operating envelope for limits, required compressor version, and accessories.
2. For medium-temperature applications, an evaporator pressure regulating valve must
be installed external to the compressor between the main suction line and the motor/
electronics cooling outlet port adjacent to the inter stage port. The recommended
valve is 7/8” (e.g., Danfoss KVP 22 or equivalent), set at a corresponding pressure to
0.8°C (34°F) saturated temperature (depending on the used refrigerant). The motor/
electronics cooling outlet port is tted with a 5/8” are adapter.
NOTE
Medium Evaporating Temperature is dened as between 0 and -10 degrees C (between 32 and 14 degrees F).
13.5.2 Low Lift
Application
Model
Cooling Mass Flow
(kg/s)
Head (kPa)
ALL 0.06 310
Table 13-2 - Low Lift Pump
Sizing
The standard TT/TG control limits compressor speed and capacity below a 1.5 pressure ratio
to ensure adequate motor/inverter cooling. When enabled, the low lift option is meant to
enable increased compressor speed and capacity at pressure ratios below 1.5. To ensure
adequate cooling for extended operation with pressure ratios below 1.5, the chiller system
must provide the subcooled refrigerant ow specied in Table 13-2. In most circumstances
and system designs, that will require the use of an OEM supplied liquid refrigerant pump.
If an adequate supply of subcooled liquid is not provided, the compressor will limit speed
and capacity to maintain safe operating temperatures. If safe temperatures cannot be
maintained, the compressor will fault. Repeated operation without adequate motor cooling
could result in damage to the compressor and evidence of such operation could limit
warranty coverage.
Refer to Figure 14-1 for a possible pump design and Table 13-2 for pump sizing. Though
each OEM may choose to use more sophisticated logic, a simplied control logic would turn
the pump on at pressure ratios below 1.5 and o when the pressure ratio rises to 1.7. By
default, the low lift option is not enabled. More details on enabling the low lift option and
the alarm and faults associated with it are included in the OEM Programming Manual.
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