Emerson SCROLL SZO44 - Manual (Page 16)

10 2006SSD-75 R4 (10/10)
Dual-Compressor Module Installation
RED
Blue
White
Yellow
+24VDC
DC common
No connection feedback
0-10VDC speed signal
2.6.2 Oil Cooler Fan Control
The Compressor Module temperature is controlled by managing module oil flow and temperature. The
module’s precise temperature control is critical to system performance and equipment life. Maintaining
proper temperature control also reduces the possibility of gas condensing into liquids during operation.
• Cooling fans require 24VDC, 4.5A (105 Watts) x 2 (9A 210W total) for the Compressor Module. Fan
speed is controlled by a 0-10VDC control signal that is applied to the yellow lead on the fan terminal
strip. Standard Compressor Modules use a nonlinear PTC thermistor to monitor oil temperature and
provide a speed signal.
• High temperature Compressor Modules use a linear NTC thermistor to monitor oil temperature. This
signal is available to support a customer-provided fan speed control circuit.
• All power connections are wired to terminal strips in a junction box on the Compressor Module.
Figure 6 Brushless DC Fan
Figure 7 Basic Fan Control System
Dropping Resistor
One Fan 100 K Ohms
Two Fans 60.4 K Ohms
PTC Thermistor
In Thermowell
The PTC Thermistor is nonlinear and switches to high
resistance in the 170-190°F (77-88°C) range.
Red Wire – 24VDC
Yellow Wire – 0-24VDC
To fan speed control
Blue Wire – DC Common