GEA Grasso - Checking the Water Circuits; Initial Startup; Fig. 17: Oil Temperature Limiter; Fig. 18: Temperatur Controlled Valve

OPERATING INSTRUCTIONS
CO
2
/NH
3
CASCADE UNIT
250 - 1000 KW
_551511_om_kas_gbr_1_.doc 19
6. The oil heater has sufficiently heated the oil
Oil temperature limiter
Voltage connection
controlled self-sufficient by control element
Before switching on the main switch, all motor
protection switches and bridge fuses within the
cascade must be switched on.
The cascade must be put into service in accordance
with the operating instructions for the compressor
control.
1. Switch on the control voltage of the compressor
control.
2. Acknowledge existing fault indications.
fig. 17: Oil temperature limiter
3. Select operating mode ”1 (manual + manual)”.
Temperatur controlled valve
4. Switch on the cascade.
controlled self-sufficient
Switching on the main switch on the switch cabinet
supplies power to all the connected electrical loads
and equipment and the SPC (programmable control)
system, including the control and display unit.
Hint!
We advise switching on the voltage in
good time before an intended startup.
fig. 18: Temperatur controlled valve
Thermostatic expansion valve
The oil-fired heating requires a lead time
in order to heat the oil in the
compressor's crankcase to temperatures
above the refrigerant's saturation
temperature. This is intended to prevent
refrigerant condensing in the compressor
and to ensure any refrigerant already in
the oil is evaporated. This ensures
sufficiant viscosity for bearing lubrication
while the compressor starts.
controlled self-sufficient
fig. 19: Thermostatic expansion valve
1.6.2.10 Checking the water circuits
Check whether the cooling and cold water pumps
are running and the shut-off fittings in the cooling
water circuit are in their operating positions.
Special features of operating mode 1 "Manual +
Manual"
Manual mode can only be realised under the
supervision of the operating personnel. The control
cycles are to be specified by the owner on their own
responsibility in compliance with the system-specific
control response.
While the unit/ chiller is operating under project
conditions, adjust the cooling water control so that
the condensing and oil temperature lies within the
permissible range.
Caution!
1.6.2.11 Initial startup
The following prerequisites must be fulfilled for the
initial start-up:
The cascade is operated manually!
The cascade operates independent of the
temperature and pressure control!
1. Main current supply available and switched on
Safety and monitoring devices are fully
functional!
2. Heat transfer medium and cooling water pumps
are switched on
3. Media flows through the heat exchangers.
4. The valves are in their "operating position"
5. Sufficient refrigerant and oil charge