Safety Devices And System Control - Bitzer KT-600-4 Manual Del Usuario

Due to the large capacity range and seasonally different ambient temperatures, a condenser pressure control is re-
quired. This largely avoids larger variations in the condensing temperature and the resulting effect on the evapora-
tion temperature. In pressure control, the following aspects should also be taken into account:
• Limiting the minimum possible condensing temperature according to the application limits of the compressors
• "Intelligent" control of the condensing temperature (as a function of load and supply air temperature) through
variable air volumes of the condenser fans. For the best possible coefficient of performance (COP), the control
algorithm should guarantee an optimum balance between the power consumption of compressors and fans un-
der all conditions.
If a desuperheater is used for heat recovery, in addition to the performance, the refrigerant-side connections must
also be taken into account, while the line cross-section must be tailored to the overall performance. The desuper-
heater may only be installed between oil separator and condenser. If used alternately as desuperheater and con-
denser, additional measures may be necessary, in order to avoid pressure-side liquid slugging and refrigerant mi-
gration.
Evaporators
Depending on the type of compound system, either individual evaporators or a larger number of evaporators will be
used. Due to the in most cases large capacity range, in particular for individual evaporators, it may be necessary to
have several refrigerant circuits controllable by solenoid valves, each of which a separate expansion valve is as-
signed to. As protection against large liquid surges during start, the suction gas line should be raised directly down-
stream of the evaporator (swan neck).
If a pump down system is in place, this measure can be omitted.
6

Safety devices and system control

Safety devices
Each individual compressor must be secured with pressure switch(es) to prevent the permitted high pressure from
being exceeded and with a protection device as well as oil pressure and oil level monitoring. In particular when op-
erating at the thermal application limit, a discharge gas temperature sensor (accessory) is additionally recommen-
ded. As protection against increased refrigerant solution in the oil at standstill, for customary applications an oil
heater (accessory) is required. A temperature-dependent control of the oil heater allows the energy requirement to
be clearly reduced.
The BITZER compressor module CM-RC-01 can secure the compressor very reliably and integrate many functions,
and the electrical installation is less complicated. Securing and operating integrated functions:
• Activation of additional fan, refrigerant injection, oil heater, start unloading, switching times of the compressor
contactors during start
• Activation of the capacity control for adjusting the cooling or heating capacity to the actual demand (via Modbus
or set point signal) – thus guaranteeing maximum compressor availability and efficiency
• Active monitoring of the operating parameters (application limits)
• Communication via the BEST SOFTWARE: Feedback via compressor operation
• Communication with system controller
• Control of the OLM-IQ ( see chapter Oil level controller OLM-IQ, page 46 )
Detailed information, assembly information and information about the electrical connection of the CM-RC-01: Tech-
nical Information KT-230 .
KT-600-4 // PDF Download 49