Cooling And Heating Logic - ABB ACS800 Series Hardware Manual

45

Cooling and heating logic

The temperature and humidity must be within allowed limits in the cabinet before the
converter can be powered up. The converter cabinet is equipped with a heating logic
which controls the cabinet heating system, allowing the converter to start only when
the operating conditions are met. When the converter is connected to the network,
normal converter power losses keep the operating temperature above the required
limit.
A simplified diagram of the heating logic is shown below. The auxiliary contact of the
relay K18 (same as K8) and contactor K16 (in power cabinet) are connected to DI4
of A43, which is used for low-temperature warning. For more detailed information,
refer to the wiring diagrams delivered with the converter.
The system has two auxiliary power inputs: one for the heating power and one for
the control power. With thermostat and hygrostat default settings, power is fed
through the heating foil of the power modules and the heaters of control unit, until
the temperature reaches +10°C inside the control unit or +11°C inside the power
modules and the humidity inside the control section drops below 80%.
The low temperature sensor is located in ACU cabinet to prevent the circuit boards
from working in a low temperature environment, and the default temperature of the
sensor is +10°C.
The module is heated by heating foil, and the power is large. The temperature inside
the module can reach the required temperature firstly during the cold start. At the
same time, a high temperature switch is connected to the power supply circuit of the
heating circuit to prevent the temperature from being too high.
ICU cabinet and module cabinet are more sensitive to humidity, therefore, the
humidity sensors are set in ICU and module cabinet respectively. Because there is
only a heating foil inside the module cabinet, the module fan will be stared when the
humidity is higher than the setting value, which helps to prevent the condensation.
The heater will be started when the humidity is too high. In order to avoid high
temperature in the ACU cabinet, when the temperature is higher than the setting
value of the temperature sensor, the heating circuit will be disconnected even if the
humidity is not reduced to the setting value.
When the heating is completed, relay K8 closes and auxiliary power is connected to
the control boards. After the control boards are booted (lasts about 1 minute), the
converter is ready to start.
When the temperature in the ICU cabinet exceeds the setting value of the
temperature sensor, the fan in the ICU cabinet will be started. The fan used for
Crowbar cooling in the ACU cabinet starts with the start of the converter, and the
cooling fan in the cabinet starts when the temperature is higher than the setting
value of the temperature sensor. The module fan starts when the converter starts.
Hardware description