DewPro<Superscript>® MMR31 Installation & Operation Manual
13
Chapter 2. Installation
2.3.4
General Wiring Instructions
below and complete the following steps:
1.
Unscrew the cap on the terminal side of the unit.
2.
Loosen the cable gland located on the side of the unit.
3.
Feed the cable through the conduit opening.
Note:
Use a standard signal cable size.
4.
Retighten the metal cable gland to meet IP 67 and to relieve any stress on the wire.
5.
Connect the wires to the MMR31 terminals as shown in
below.
6.
Verify that a voltage between 12 and 28 VDC is present across the terminals and –.
Note:
This is the voltage that is actually measured across the MMR31 terminals. It is not necessarily exactly the
same as the power supply voltage, due to voltage loss in the wires, displays, indicators, etc.
7.
To meet EMI/RFI immunity requirements, a four-wire shielded cable with a common foil shield layer is used to
power the MMR31. To clamp the shield foil in the metal cable gland, remove 3 in. (75 mm) of the insulation and
fold back the foil. The ground wire must be connected to the internal grounding screw.
GND
LOOP 1
–+
+
–
+
–
24 VDC Nominal (12–28V)
24 VDC Nominal (12–28V)
External GND/SHIELD Connection
Internal GND Connection
LOOP 2
+
–
Figure 10: Electrical Connections - Two Current Loops