Carrier TRANSICOLD Vector 8500 Operation & Service Manual Download

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4–7

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NOTE

I n C o n t i n u o u s R u n , w h e n d i ff e r e n c e
between ambient and setpoint is < 10°C, the
COMPRESSOR RESTART OFFSET config-
uration value will be used for the switch point
to turn cool on (instead of 0.2°C). If the
ambient and setpoint are more than 10°C
then the switch point remains 0.2°C.

4.7.4

Cool Mode

When Cool Mode is required the system will operate in
Pulldown or CSMV Control. Pulldown operation will
include periods of time in Economized Mode and Stan-
dard Mode. CSMV control will occur in Standard Mode.
For descriptions of operation when cooling, with flow
diagrams, refer to

Section 2.13

Pulldown

Pulldown will be entered:

• following a Start

−

• following a Setpoint change (requiring additional

cooling)

• following an operational change (Start

−

Stop vs

Continuous or Engine Operation vs Electric
Operation)

• following a defrost termination

• or when all other Stop Parameters have been

met except the refrigerated compartment Tem-
perature Stop Parameter

Pulldown will end when one of the following occurs:

• when in Engine Operation and the control sys-

tem is calling for low speed

• when in Start

−

Stop and the refrigerated com-

partment Temperature Stop Parameter has
been satisfied while one or more of the other
Stop Parameters has not been satisfied

• If in Continuous Operation - perishable and the

High Speed Pulldown Configuration is OFF and
the temperature is in the required range. This
range is calculated when Supply Temperature
(ST) is equal to or less than the Return Tem-
perature (RT). The calculation is:

Off Value = (ST

−

RT)/2

When the Control Temperature is within a
range of +/

−

the Off Value of set point, Pull-

down Mode ends.

• If in Continuous Operation - Perishable, and the

High Speed Pulldown Configuration is ON: when
the temperature is equal to setpoint.

• when active probe is within the control tempera-

ture which allows the unit to shut off.

CSMV Control

CSMV Control will be entered when additional cooling

is required and Pulldown is not allowed. In CSMV Con-

trol the valve will be modulated so as to balance com-

pressor capacity with the refrigeration load.

4.7.5

Heat Mode

When Heat Mode is required the system will operate

with the evaporator fans energized. Operation of the

heaters is determined in accordance with the calcu-

lated Controlling Temperature value (CT) and the dif-

ference between this value and Setpoint (SP) in

accordance with the following:

HTCON1 may also be activated when the unit is in Con-
tinuous Operation Cooling to assist in balancing unit
capacity with the load. In all other operating states and
modes HTCON1 and HTCON2 will not be activated.

4.7.6

Null Mode

For descriptions of operation in the Null Mode, refer to

Section 2.13

and

Section 4.7.3

Control Temperature with Fuel Saver OFF

HTCON1

Switch On

when CT- SP is

less than -0.54°F (-0.3°C)

Switch Off