Carel MuChiller UCHBD00001130, Руководство пользователя

Страница: 59 / 108

Below are details of the various actions to prevent the operating limits from being exceeded; action 1
refers to the control action (before exiting the envelope); action 2 to the limiting action (working point
already outside of the envelope).
Low evaporation pressure prevention (zone 2)
The low evaporation pressure limit for the prevention action is determined by maximum between:
l
the nominal compressor threshold (BLDC only);
l
the threshold set by the "Manufacturer": par. C018/P000 for On-Off/BLDC compressor;
l
the frost protection limit, depending on the operating mode: par. U050 in cooling mode and S057 in
heating mode with water/water units.
Device Description
BLDC compressor
1. Decrease the rate of capacity increase.
2. Limit capacity
Tandem on-off compressors
1. -
2. Shutdown a compressor
ExV -
Fan -
High compression ratio prevention (zones 3-4)
A high compression ratio is a thermal limit of compressor operation: normally control is activated at the
limit of the envelope, reducing capacity when the limit is exceeded; if a probe is fitted to measure
discharge temperature (HP version only) and if the temperature approaches the limits, compressor
capacity will be modulated so as to managed the critical condition. A specific algorithm initially slows
down the increase in capacity, until stopping it completely when at the set point (5°C below the
maximum limit); if the temperature increases further, the algorithm gradually and slowly reduces
capacity, taking into account compressor thermal inertia.
Key
Td Discharge temperature
HT Low discharge temperature alarm threshold
CT High discharge temperature control threshold
DT Control action deviation
AL High discharge temperature alarm zone
Z3 Capacity reduction zone
Z2 Acceleration control zone
Z1 Normal operating zone
Device Description
BLDC compressor
1. Decrease the rate of capacity increase.
2. Limit capacity
Tandem on-off compressors -
ExV valve -
Fan -
ENG
µC0300053EN rel. 1.0 – 23.07.2018
5. Functions | 59