Water Control - Hitachi SAMURAI Series Service Manual

2 Control Functions
Control functions on the module

2.1.1 Water control

Outlet water temperature of Chiller Unit is detected by Thermistor, and based on this value, compressor ON/OFF and the
most suitable capacity is determined. Following shown the continuous capacity control and change of water temperature.
Starting setting
(example)
Tsc : 7ºC
temperature
T1: 1ºC
T2: 2ºC
T3: 2ºC
T4: 1ºC
Tsc+ T2/3+ T4
9ºC
T4
Tsc+ T2/3
8ºC
Tsc (setting t.)
7ºC
T3
(0.5~5.0ºC)
Tsc- T2/3
6ºC
T1
Tsc- T2/3- T1
5ºC
Load up I
status

Method of outlet temperature detection
1 Load-up I control at over 9°C (The capacity is changed a lot in order to approximate the target temp. quickly)
2 Load-up II control at 8~9°C (The capacity is changed moderately)
3 In neutral zone (6~8°C), load is balanced and performance is not changed.
4 Under neutral zone (below 6°C) load-down control is performed and performance is decreased.
5 Stop temp: Compressor is stopped at 5°C. The inlet temp of that time is saved.
6 When inlet temp becomes 2°C higher than that of at stop, re-start signal is output and unit is re-started after at least 3
min guard.
9 SMGB0120 rev.0 - 11/2017
Outlet
Inlet
temperature
T4
(1.0~3.0ºC)
T3
T1
(0.5~2.0ºC)
Load up II
Neutral status
status
Memorizes the inlet temperature
at Thermo-OFF and re-start at
∆T2
T2
(1.0~4.0ºC)
T2
Stop
Neutral
Load-down status
status
status
Stop Start
(Thermo off) (re-start)
Load up I zone
Load up II zone
Neutral zone
Load Down zone
Thermo-off zone
Load up II
Neutral status
status
2