Carrier 48FK, JK034-074, 50FK specifications Switch Functions, Tubing Size

Table 7 Ð Switch Functions

	SWITCH		CONFIGURATION		VOLTAGE	FUNCTION
	NUMBER
	SW-1			N.C.	115	Deenergize 115-v (OFC, Comp, IFC, Electric Heaters)
	SW-2			N.C.	115	Deenergize TRAN7 (Process Board)
	SW-3			N.O.	24	Energize EOR (Open Economizer Outside Air Dampers)
	SW-4			N.O.	115	Energize IFC and CR-3 (IGV/VFD)
	SW-5			N.C.	115	Isolate IFC and PEC for Separate Operation
	SW-6			N.O.	115	Energize PEC (Power Exhaust)
	SW-7			N.O.	24	Open PED at DPS
	SW-8			N.C.	24	Block Auto-Close at DPS (Due to Low BP)
	SW-9A/B			A: N.O.	115 max	Signal Room Terminals to Open (HIR1)
				B: N.C.
		LEGEND
BP	Ð Building Pressure
DPS	Ð Differential Pressure Switch
EOR Ð Economizer Open Relay
HIR	Ð	Heat Interlock Relay
IFC	Ð	Indoor Fan Contactor
IGV	Ð	Inlet Guide Vane
N.C.	Ð	Normally Closed
N.O.	Ð	Normally Open
PEC	Ð Power Exhaust Contactor
PED	Ð Power Exhaust Damper
OFC	Ð Outdoor Fan Contactor
VFD	Ð Variable Frequency Drive

Air Pressure Tubing Ð Before options such as inlet guide vanes (IGV), variable frequency drive (VFD), and/or modulating power exhaust can operate properly, the pneu- matic tubing for pressure sensing must be installed. Use ®re- retardent plenum tubing (®eld-supplied). Tubing size depends on type of control device (see Table 8 below). Tubing must be run from the appropriate sensing location (in the duct or in the building space) to the control device location in the unit.

Table 8 Ð Tubing Size

OPTION	UNITS	NOMINAL TUBE
		SIZE (in.)
Inlet Guide Vanes (IGV)	ALL	3¤8
Variable Frequency	ALL	1¤4
Drive (VFD)
Modulating Power Exhaust	FK,FKX,JK,JKX	3¤8

INLET GUIDE VANES Ð The tubing for the duct pressure (DP) control option should sample supply duct pressure about 2¤3 of the way out from the unit in the main trunk duct, at a location where a constant duct pressure is desired.

The inlet guide vanes are controlled by a differential pres- sure switch (DPS). On sizes 034-048, the DPS is located in the auxiliary control box at the economizer end of the unit (see Fig. 33). On sizes 054-104, the DPS is located in the supply fan section. See Fig. 34. Use a nominal 3¤8-in. plastic tubing.

VARIABLE FREQUENCY DRIVE Ð The tubing for the duct pressure (DP) control option should sample supply duct pressure about 2¤3 of the way out from the unit in the main trunk duct, at a location where a constant duct pressure is desired.

The duct pressure is sensed by a pressure transducer. The pressure transducer output is directed to the VFD. On 034- 048 units the DP transducer is located in the auxiliary con- trol box. On 054-104 units, the DP transducer is located in the supply fan section. See Fig. 34. Use a nominal 1¤4-in. plastic tubing.

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