MICRO-AIR Artic Air 24 Przewodnik Instalacji Pobierz pdf (Strona 43)

By flipping the switches ON and OFF it is possible to activate and de-activate either box

independently of the other. To shut down a box, move the toggle switch down to the OFF

position. The digital display for this box will go dark.

When all switches are in the "OFF" position the compressor will not be turned on even when the

temperature of the plate has risen. This may serve as a safety mechanism when working on or

near the compressor unit.

The System Circuit Breakers

There are two (2) 10 amp circuit breakers in the base of the unit. They are of the manually re-

settable type and are visible on the right side of the base. The left side circuit breaker provides

safety to the control circuitry current. The right side circuit breaker controls the seawater pump.

Tripplng the water pump circuit breaker will result in the pump shutting down, which in turn, will

cause the HP cut-out to trip (see trouble shooting). Tripping the left side circuit breaker will cause

the control circuitry to lose power and the entire system to shut down immediately.

The High-Pressure (H-P) Cut-Out

The H-P cut-out is a safety switch which automatically shuts down the system in an over-

pressure (above 400 psi) situation. Generally, an over-pressure condition occurs due to loss of

cooling water from a failure of sea water pump or loss-of-prime (centrifugal type pumps only).

However, the H-P cut-out will also trip if the system has been severely overcharged with

refrigerant, if air was accidentally introduced into the system during service or (in older systems)

the condenser has not been cleaned.

Note: If the H-P cut-out activates, the system will typically run for a minute or two then shut off for

5-15 minutes until the pressure bleeds down to 300 psi, then repeat the cycle until the problem is

corrected. Each time the system shuts off the digital displays on all controllers will go dark.

The Low-Pressure (L-P) Cut-Out This will shut down the system if the pressure falls below 5

psi. This can happen if refrigerant is lost due to a leak or if the system has run long enough to

pull the plates so cold that the gas pressure falls below the shutdown point. If the system is out

of gas, it won’t cool the plates. If there is still refrigerant in the system, when the pressure rises

above 20 psi, the low pressure cutout will reset and the system can restart.

Determining the state (frozen or thawed) of the Holding Plate

The Glacier Bay system uses a true eutectic holding solution in the holding plates. The term

“true eutectic” means that the solution freezes and thaws at a single temperature (For example,

water at 32

F/0

C for example). Our TSS +26 refrigerator solution changes state at +26

F (-3

C). Our TSS -8 freezer solution changes state at -8

F (-22

C). Knowing that, one would think

that it would be a simple matter to know if the plate is frozen or thawed by simply measuring

whether the plate temperature is above or below the eutectic point (ie. freeze/thaw temperature).

Unfortunately, it is not possible to measure the actual eutectic temperature from outside the

holding plate.

When the compressor is running (and the holding plate is freezing down) the temperature probe

is actually reading a combination of the eutectic solution temperature and the (much colder)

evaporator coils inside the holding plate. Consequently, the holding plate temperature measured

while the compressor is running will always be colder than the eutectic solution itself. Exactly

how much colder varies several degrees between different systems and installations.

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