Crankcase Heaters — Crankcase heaters are energized as long as there is power to the unit, except when the compres- sors are operating.

IMPORTANT: Unit power must be on for 24 hours prior to start-up. Otherwise, damage to compressor may result.

Variable Frequency Drive (VFD) — The variable frequency drives are factory set. These settings include factory- installed jumpers and software configurations. The only field configured set point is duct static pressure. A Toshiba Opera- tion Manual is shipped with each VAV unit. This manual should be used if the drive needs to be customized for a partic- ular application.

NOTE: The VFD will always provide the proper phase sequence to the indoor-fan motor. The indoor-fan motor oper- ates in proper rotation regardless of the phase sequence to the unit. If, upon start-up, the outdoor fans operate backwards but the indoor fan operates in the correct direction, reverse any two leads to the main terminal block. All fans will then operate in the correct direction.

A factory-supplied 2-wire duct pressure transducer is sup- plied and wired complete with cable ground to reduce electrical noise. A 1/4-in. air pressure tube must be routed to a location in the supply air ductwork where it can sense supply air duct pres- sure. The recommended location is about 2/3 of the way out on the supply ductwork, so that a steady pressure will be provided for the transducer.

To set the duct static pressure, perform the following steps. The factory setting is zero. The duct transducer has a range from 0 to 5 in. wg. The transducer output is 4 to 20 mA, there- fore, 0 to 5 in. wg is proportional to the 4 to 20 mA and must be expressed to the VFD in terms of percentage of the frequency range. Refer to Table 11. The set point value is a percentage of the maximum output frequency. Locate the duct static pressure closest to that desired and use the corresponding set point val- ue. If necessary, interpolation between duct static pressures is permissible.

Table 11 — Toshiba TOSVERT VFD Set Point (Frequency Command) for Supply Duct Pressure

PRESSURE

 

CONTROL SIGNAL

VFD SET POINT

in. wg

kPa

 

(mA)

(Hz)

0.0

0.000

4.0

0

0.25

0.062

4.8

3

0.50

0.124

5.6

6

0.75

0.187

6.4

9

1.00

0.249

7.2

12

1.25

0.311

8.0

15

1.50

0.373

8.8

18

1.75

0.435

9.6

21

2.00

0.498

10.4

24

2.25

0.560

11.2

27

2.50

0.622

12.0

30

2.75

0.684

12.8

33

3.00

0.747

13.6

36

3.25

0.809

14.4

39

3.50

0.871

15.2

42

TOSHIBA TOSVERT130-E3 VFD — The VFD must be powered up, however, since it is located near the indoor fan, operation of the fan is not desirable. To disable the fan and set the duct static pressure, perform the following procedure:

1.Open the Indoor Fan Circuit Breaker (IFCB). This will shut off power to the VFD.

2.Wait for the VFD display to go blank and remove VFD cover without touching any interior components. Make sure that the charge indicator lamp is out, indicating that the VFD is discharged. The lamp is located on the upper right hand corner of the terminal block. It may take sever- al minutes for the VFD to fully discharge.

A high voltage potential can exist with the indoor fan cir- cuit breaker open. The charge LED, located in the top right-hand corner of the Toshiba TOSVERT130-E3 VFD control board, will indicate charged capacitors. DO NOT TOUCH internal high voltage parts if LED is lit.

3.Remove jumper between ST and CC on the terminal block and replace the VFD cover. This will disable the running of the VFD. Refer to Fig. 57.

4.Close the IFCB and energize the Indoor Fan Contactor (IFC). The VFD is now powered but the fan will not operate.

5.On the front of the VFD is a keypad, which is used to change the VFD set point. At this point the drive should be disabled and the display read “OFF”. If the current output frequency is displayed then verify that the ST and CC jumpers have been removed.

6.Press either the “DOWN ARROW” or “UP ARROW” key once, this will display the current frequency set point.

7.Press either the “DOWN ARROW” or “UP ARROW” key to change set point to the appropriate duct static set point desired. This number may be adjusted based on the amount of static pressure (in. wg) required. Refer to Table 11 to identify the VFD Set Point.

DP

 

 

 

 

 

 

P24

RES

RR F

R S1

S2

S3 S4

RCH P24 LOW LOW

ST

FM

AM CC

CC

RX

PP IV

FP FLC FLB FLA

 

 

 

 

 

+

 

 

 

 

 

 

DP

 

NOTES:

1.Drive enable (ST to CC made).

2.No emergency off command (S4 to CC made).

3.Direction command (F or R to CC made).

4.Frequency reference (4-20mA signal at IV terminal).

Fig. 57 — Toshiba TOSVERT130-E3 VFD

Factory-Installed Jumpers

59

Page 58 Page 60
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Image 59
Carrier 48AY020-060, 48EW, 48EY024-068, 48AW, 48EK, 48AK, 48AJ, 48EJ specifications Pressure Control Signal VFD SET Point, In. wg
Page 58 Page 60

48EJ, 48AJ, 48AK, 48EK, 48AY020-060 specifications

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