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TVP Manual (full) March 2007 CE rev 03.doc
1.106 System Recovery after defrost
After defrost it is possible to enter cool immediately however, better results (faster cycle times
and lower temperatures) are achieved if a short period (more than 4 minutes) in standby is
allowed for the system to recover. The recovery period is in proportion to the defrost
termination temperature and the duration of the defrost cycle. A longer defrost period and the
higher termination temperature both increase the recovery period. A good rule of thumb is if
the discharge pressure is less than 160 psi then it is fully recovered.
Remote display of system status in manual mode can be achieved by using the system
condition signals from the remote interface, which remain active at all times. The analog
output also reads the coil out condition.
1.2 Remote mode operation of a TVP using the 37 pin isolated interface
All buttons apart from scroll and the emergency off button are disabled by connection of the
remote. The system automatically switches to remote operation if a link between pin 9 and
24 is made, this link is already made in the mating connector supplied with the TVP.
The remote is a fully isolated interface and mirrors the operation of the front panel. Making a
connection between a system ground pin and the appropriate command pin will change the
systems function.
Read back of system function is retained by the buttons on the front panel becoming
illuminated. The system also has read back through the remote connector via relays.
For process safety reasons the interface has the following command hierarchy:
COOL – Overrides all other actions.
DEFROST – Will revert to standby when complete.
STANDBY – Default state.
When the remote connector is fully engaged the system will automatically switch from “local”
to “remote” operation. This is indicated on the front panel display. When in remote operation
all control buttons apart from the STOP / EMERGENCY OFF and SCROLL buttons are disabled.
WARNING
Always isolate the system through the main circuit breaker before attaching the remote
control. When in remote operation take additional care to prevent personal injury.
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