070.610-IOM (JUL 21)
Page 16
RWF II Rotary Screw Compressor Units
Installation
Minimum burden ratings
The following table gives the minimum CT burden ratings.
This is a function of the distance between the motor start-
ing package and the compressor unit.
Table 8: Burden rating and maximum panel distance
Burden rating
Maximum distance from Frick
panel
ANSI
VA
Using #
Using #
Using #
14 AWG
12 AWG
10 AWG
B-0.1
2.5
15 ft
25 ft
40 ft
B-0.2
5
35 ft
55 ft
88 ft
B-0.5
12.5
93 ft
148 ft
236 ft
Control power regulator
Compressor units that will be used in areas that suffer
brownouts and other significant power fluctuations can be
supplied with a
control power regulator. See the following
Figure.
Figure 19: Suggested regulator installation
Installation of electronic equipment
in an industrial environment
In today’s refrigeration plants, electronic controls are part
of almost every aspect of refrigeration control. Electronic
controls have brought to the industry more precise con
-
trol, improved energy savings, and operator conveniences.
Electronic control devices have revolutionized the way
refrigeration plants operate.
The earlier relay systems were virtually immune to radio
frequency interference (RFI), electromagnetic interference
(EMI), and ground loop currents. As a result, installation
and wiring were of little consequence and the wiring job
consisted of hooking up the point-to-point wiring and
sizing the wire correctly. In an electronic system, incorrect
installation causes problems that may outweigh the bene
-
fits of electronic control. Electronic equipment is suscepti
-
ble to RFI, EMI, and ground loop currents, which can cause
equipment shutdowns, processor memory and program
loss, and erratic behavior and false readings. Manufactur
-
ers of industrial electronic equipment take into consider-
ation the effects of RFI, EMI, and ground loop currents and
incorporate protection of the electronics in their designs.
However, these design considerations do not make the
equipment immune, so manufacturers require certain
installation precautions, to protect the electronics from
these effects. As a result, view all electronic equipment as
sensitive instrumentation that requires careful attention to
installation procedures. These procedures are well known
to instrumentation, networking, and other professions but
may not be followed by general electricians.
There are a few basic practices that if followed, will mini-
mize the potential for problems resulting from RFI, EMI
and/or ground loop currents. The National Electric Code
(NEC) is a guideline for safe wiring practices, but it does
not necessarily deal with procedures used for electronic
control installation. Use the following procedures for
electronic equipment installation. These procedures do
not override any rules by the NEC, but are to be used in
conjunction with the NEC code and any other applicable
codes.
With exclusion of the three phase wire sizing, use Frick
drawing
649D4743
as a reference for properly sizing con
-
trol wires and other wiring specifications.
Throughout this document the term Electronic Control
Panel is used to refer to the microprocessor mounted
on the compressor package or a Central Control System
panel.
NOTICE
It is very important to read the installation instruc-
tions thoroughly before beginning the project. Make
sure you have drawings and instructions with your
equipment. If not, call the manufacturer and re-
quest the proper instructions and drawings. Every
manufacturer of electronic equipment should have a
knowledgeable staff, willing to answer your questions
or provide additional information. Following correct
wiring procedures will ensure proper installation and
consequently, proper operation of your electronic
equipment.
