GEA Bock FK50 - Manual (Page 20)

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7| Accessories
7.1 Capacity regulation
FK50 / ... ... N + TK ... K
Designation Item No. Item No.
Special accessory 12 V 08703 08708
Special accessory 24 V 08704 08709
For a description, see technical information "Capacity regulation" (Item No. 09900)
If the capacity regulator is factory-fitted, it is integrated into an extra, dedicated cylinder cover. For
retrofits, it is supplied with the cylinder cover. The regulator closes one cylinder bank at a time (capacity
regulation approx. 33 %). Two retrofit kits are required for a capacity regulation of approx. 66 %.
A screw-in option is provided for the sensor element on the hot gas side of the compressor
housing (see Chap. 9). Connect the thermal protection thermostat in series with the control line.
Technical Data:
Switching voltage max. : 24 V DC
Switching current max. : 2.5 A at 24 V DC
Switch-off temperature : 145 °C ± 5 K
Switch-on temperature : approx. 115 °C
7.2 Thermal protection thermostat (Item No. 07595)
ATTENTION! Capacity-regulated operation alters the gas speeds and pressure
ratios of the refrigerating plant: Adjust the suction line routing and
dimensioning accordingly, do not set the control intervals too close and
do not let the system switch more than 12 times per hour (refriger-
ating plant must have reached a state of equilibrium). Continuous
operation in the control stage is not recommended as the gas
velocity in the plant system under certain circumstances does not
guarantee sufficient oil return to the compressor with activated
capacity regulator for a compressor speed below 1200 - 1500 rpm.
We recommend switching to unregulated operation (100% capacity)
for at least 5 minutes per capacity-regulated operating hour. An
assured oil return can also be realised by a 100% capacity require-
ment after each compressor restart as otherwise the compressor
can also be shut down in the regulated operating time by the
thermostat.
Electrical actuation of the solenoid valve: Normally open, (corre-
sponds to 100 % compressor capacity).
Cylinder covers for capacity regulation are marked with the
designation "CR" (Capacity Regulator).