Elstat EMS-55, Technical Instruction Manual, Page: 11 / 26

11
Disconnect the power to the control (unplug the cooler), push and hold the set and defrost buttons
and restore the power. Keep the buttons pressed until the display shows the temperature again,
release the buttons and the reset will be complete. (During this procedure there will be a short period
when the display is blank).
The control will then start to relearn. If the parameter AF default setting is
3 then the control will relearn its activity frequency. This reset is only applicable if the compressor is
renewed or the default parameters need to be restored.
SOFT START FUNCTION
When a motor starts the start up current can be up to 6 times the running current, which means that
when a compressor starts the current drawn could be up to 36 amperes for a running current of 6
amps (This inrush will only last a few milliseconds).
This start-up current in an electric motor is unavoidable but yet the total inrush current can be
minimised by starting the motors at intervals. For example, rather than 2 motors starting at the same
time they can be started separately and this is exactly what the EMS does so as to minimise the start-
up current.
The delay between the start of the compressor and evaporator fans is approximately 20 seconds (this
value is not programmable).
MINIMUM COMPRESSOR REST TIME
This feature is designed to avoid unnecessary damage to the compressor (the most expensive
component) of the refrigeration system. When the compressor runs it generates a head pressure and
a back pressure in the refrigeration system. This pressure remains in the system for a period when
the compressor stops but it slowly equalises due to leakage in the valves. Testing has shown that
equalisation of these pressures takes approx. 2 minutes and it is for this reason that the EMS has a
minimum compressor rest time. (This value is adjustable by means of parameter RT and its default
setting is 3 minutes).
The minimum compressor rest time avoids:

High peak current through the windings of the compressor motor

Switching off on the thermal overload protection

Short cycling of the system