Fridgewatch 2100 Controller Mk4
Section 3
Publication 3-58
Issue 1.1 : 01/08
Page 107 of 152
NOTE: the value assigned to S65 Inhibit Loading must
normally be smaller than the S66 Force Unload.
If motor current display is used (S64 enabled) but current limiting is not
required, set S65 to a higher value than S64.
S66 P5 (compressor 1 current limit 2): force unload (units: Amp)
With S64 enabled, S66 defines the motor current limit above which
Fridgewatch 2100 sends continuous unload pulses until the motor current
falls below this limit; this overrides the output from the PID algorithm or
external load/unload signals.
NOTE: the value assigned to S66 Force Unload must
normally be larger than the S65 Inhibit Loading.
If motor current display is used (S64 enabled) but current limiting is not
required, set S66 to a higher value than S64.
S67 P5 (0 to 1 V/4 to 20 mA signal analogue input 2 on 3MIO2 card)
for compressor 2: unused/current transformer ratio/motor line
current at 20 mA signal
Measured point P5 can be used to display motor current and provide the
current limiting function (internal current limiting). There are two different
methods:
0 to 1 V ac signal from a motor current transformer (CT).
Use a 1 Amp CT with a 1
Ω
(1 R 0) resistor connected across its
terminals, thus producing 1 volt across the Fridgewatch 2100 input
at the CT maximum rating. Set S67 = motor line current at 1 V ac
(equal to the CT ratio). Fridgewatch 2100 now displays motor
current as P5 and takes care of current limiting internally using the
current limits defined by S68 and S69.
4 to 20 mA signal from a motor soft-starter or inverter.
Fit a 50
Ω
shunt resistor across the Fridgewatch 2100 input and
set S67 = -1 x motor line current (not phase current) corresponding
to the 20 mA signal. The negative (-) sign instructs Fridgewatch to
scale motor current between 0 Amp when the signal is 4 mA to
ABS (S67) when the signal is 20 mA.
Set S67 = 0 if motor current display is not used. If current limiting is still
required this must be done via digital inputs from a remote contact
ammeter.
S68 P5 (compressor 2 current limit 1): inhibit loading (units: Amp)
With S67 enabled, S68 defines the motor current limit above which
compressor loading is inhibited.
NOTE: the value assigned to S68 Inhibit Loading must
normally be smaller than S69 Force Unload.
If motor current display is used (S67 enabled) but current limiting is not
required, set S68 to a higher value than S67.
S69 P5 (compressor 2 current limit 2): force unload (units: Amp)
With S67 enabled, S69 defines the motor current limit above which
Fridgewatch 2100 sends continuous unload pulses until the motor current
falls below this limit; this overrides the output from the PID algorithm or
external load/unload signals.
NOTE: the value assigned to S69 Force Unload must
normally be larger than S68 Inhibit Loading.
