6.3 Defrost lasts as long as the time DTO but, if the evaporator probe is active (T2=YES) and temperature DLI is achieved before this time elapses,
defrost will be terminated in advance.
Now, if DRN is greater than 0, before cooling starts all outputs will remain off for the time set to DRN. This phase, called drain down, will allow a
complete ice melting and the drain of the resulting water.
7. EVAPORATOR FANS
7.1 During temperature control the evaporator fans are controlled by the parameter FPC. If it’s greater than 0, the fans follow the compressor cycle:
they turn on simultaneously with the compressor, but fan run continues after the compressor has gone off for a time proportional to its run and the parameter
FPC. One unit of FPC corresponds to 20% of compressor run, therefore, for example, with FPC=2 compressor and fans start at the same time and if the
compressor runs for 6 minutes, then the evaporator fans will run for a total time of 6+2 minutes and 24 seconds (40% of 6 minutes).
With FPC=0 the fans are not stopped by the proportional control.
7.2 If the SSD90 is connected to a door switch and you set parameter DS to YES, when the door is opened the evaporator fans stop. This control only
takes place during temperature control.
7.3 After defrost, if probe T2 is active (T2=YES), temperature FDD establishes evaporator fan re-start. In other words, the fans start again when the
evaporator has got a temperature lower than FDD. If this condition is not met within 3 minutes following defrost termination, the fans will however re-start.
8. ALARMS
The SSD90 allows a check on the correct thermostat operation, the door being left open, condenser periodic cleaning, in addition to the functional alarms
because of power failure and probe fault. When an alarm takes place, the controller switches on the relevant relay and buzzer, flashes the alarm sources
on display (see 2.3).
By pressing button , the buzzer is silenced, after that if the alarm persists, it will periodically come on for 20 seconds every hour, until the alarm ends
(however the display indications and the relay always remain on). The acoustic warning re-triggering applies to all alarms with the exception of the
condenser cleaning. Hereinafter is a description of the operation of the various sections:
8.1 ATL determines the alarm differential for temperatures lower than setpoint (cooling) or setpoint + hysteresis (heating) and ATH is the alarm
differential for temperatures higher than the setpoint (heating) or setpoint + hysteresis (cooling). By setting to 0 one or both differentials you exclude the
corresponding alarm.
Example 1: SP=-20, HYS=02, ATL=-05, ATH=05; the alarm thresholds are set to –25° and –13°.
Example 2: SP=70, HYS=-04, ATL=-05, ATH=05; the alarm thresholds are set to +61° and +75°.
The alarm signalling can be immediate or delayed by the time ATD if this is greater than 0.
During defrost, the high temperature alarm is excluded.
8.2 By enabling door switch control, DS=YES, you also enable the relevant alarm function. Therefore, as described in 7.2, when the door is opened,
the fans will be stopped immediately and after the delay time ADO, the compressor will be stopped too and the alarm will be signalled.
8.3 By setting parameter ACC to a value greater than 0, you enable a periodic condenser clean warning. In other words, when the timer counting the
compressor running time matches the weeks programmed with ACC, the display will show a condenser clean request.
Example: with ACC=16 you will obtain a warning every 16x7x24=2688 hours of compressor operation. In other words, supposing that the
compressor runs for 5 minutes and rests for 5 minutes, there will be a warning after about 32 weeks.
You can only reset the timer when you have a warning, in other words after the timer has achieved the programmed time. Therefore proceed as
follows: 1) press button and put the controller on a standby; 2) clean the condenser; 3) press button and button simultaneously. If the standby
function has not been enabled, go to point 2 directly.
9. LIGHT SWITCH AND SERIAL COMMUNICATION
9.1 The relay controlling the lights can alternatively be controlled manually by means of button (SMD34 only) or, if the switch is fitted, automatically
when the door is opened. In this case, the parameters DS and LDO must both be set to YES. As described at 2.1 the light operation is independent from
the standby.
9.2 The SSD90 can be fitted with RS485 serial port allowing the controller to exchange information with a supervisory software like the TAB. All the
temperatures, status and control parameters are available for the PC client. The identification of every single unit within the network is given by parameter
ADR.
WARRANTY
LAE electronic Srl warrant that their products are free of any defects in workmanship and materials for a period of 1 (one) year from date of production
shown on the enclosure. LAE electronic Srl shall only repair or replace those products of which defects are due to LAE electronic Srl and recognised by their
technicians. LAE electronic Srl are not liable for damages resulting from malfunctions of the products.
Defects due to exceptional operating conditions, misapplication and/or tampering will void the warranty.
All transport charges for returning the product to the manufacturer, after prior authorisation by LAE electronic Srl, and for the return to the purchaser are
always for the account of the purchaser.
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