Fridgewatch 2100 Controller Mk4
Publication 3-58
Section 3
Page 106 of 152
Issue 1.1 : 01/08
S63
V
ALUE
R
EMARKS
0
Disables scanning of the P4 inputs on all compressor cards.
1
Fridgewatch 2100 uses the LVDT 4 to 20 mA signal for display purposes only. The slide valve position, P4,
as a percentage of the slide travel is not used for any control functions.
2
The P4 4 to 20 mA input is not used for capacity control. A different 4 to 20 mA transmitter is fitted and
displayed at P4; the range of the ‘other’ transmitter is defined by settings S84 and S85. The transmitters on
all compressor cards must have identical ranges.
3
Fridgewatch 2100 uses the LVDT 4 to 20 mA signal to provide feedback of the current slide valve position.
Refer to the limitations described in the NOTE below.
For manual capacity control modes, Fridgewatch 2100 provides timed pulses in the required direction (load
or unload).
4
As S63 = 3 with the addition that P4 can be calibrated in software for applications where calibration is not
provided on the LVDT and the normal range of P4 calibration is not sufficient. Refer to the limitations
described in the NOTE below.
NOTE The single value of S63 applies to ALL compressors controlled by a single Fridgewatch 2100 panel. This results in
two limitations:
1) For multiple compressors connected to one Fridgewatch 2100 panel, if ONE compressor uses the LVDT
4 to 20 mA signal on P4 for slide valve position, ALL compressors must use P4 for slide valve position.
If ONE compressor has only minimum, intermediate and maximum slide valve position switches, ALL compressors
must use switch contacts even if this requires multiple trip amplifiers to be fitted to the 4 to 20 mA circuits on other
compressors to provide these contacts.
2) For multiple compressors connected to one Fridgewatch 2100 panel using LVDT 4 to 20 mA signals on P4 for
slide valve position, if ONE compressor has no calibration on the LVDT (S63=4), then the calibration procedure
described in 12.5. Calibration of LVDT 4 to 20 mA Signal – HS 3100 New Series, HS 3200 and HS 4200 Series
Compressors must be carried out for ALL compressors even if they have on-board LVDT calibration.
Table 14 Slide Valve Position Options - Values For S63
S64 P5 (0 to 1 V/4 to 20 mA signal analogue input 4 on 3MIO1 card)
for compressor 1: 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 S64 = 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 S65 and S66.
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 S64 = -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 (S64) when the signal is 20 mA.
Set S64 = 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.
S65 P5 (compressor 1 current limit 1): inhibit loading (units: Amp)
With S64 enabled, S65 defines the motor current limit above which
compressor loading is inhibited.
