Electrical Considerations - Emerson Rosemount Apex Reference Manual

Reference Manual
00809-0100-4731, Rev FA
April 2003

Electrical Considerations

Refer to Safety Messages on page 2-2 for more information.
™
APEX and APEX Sentry
To set the switches, follow these steps:
1. To access the switch bank on the microprocessor board
(Figure 2-18), remove the cover opposite the terminal side, or remove
the optional integral display (if installed) from the gauge. Do not remove
the gauge cover in explosive atmospheres when the circuit is alive.
2. To set the 4–20 mA alarm output to low, move Switch 1 to the OFF
position. High (ON) is the factory default setting (see Figure 2-18).
3. To enable the security write protection feature, move Switch 2 to the ON
position (top). The OFF (low) option is the factory default setting
(see Figure 4-1).
4. Reinstall the display (if necessary) or replace the cover.
Conduit Connections
The electronics housing has two ports for
Adapters are also available for PG 13.5 or CM20 conduit. These connections
are made in a conventional manner in accordance with local or plant electrical
codes. Be sure to properly seal unused ports to prevent moisture or other
contamination from entering the terminal block compartment of the electronics
housing.
NOTE
To ensure long life for your radar gauge, and to comply with hazardous
location installation requirements, tighten covers on both sides of the
electronics housing to achieve metal-to-metal contact.
NOTE
In some applications it may be necessary to install conduit seals and arrange
for conduits to drain to prevent moisture from entering the wiring
compartment.
Grounding the Gauge Housing
The electronics housing should always be grounded in accordance with
national and local electrical codes. Use the equipment only as specified in this
manual. Failure to do so may impair the lightning and transient protection
provided by the equipment. The most effective grounding method is to
connect the grounding lug on the gauge directly to earth ground with 1 ohm or
less impedance.
The Internal Ground Connection (Protective Ground Connection), located
inside the FIELD TERMINALS side of the electronics housing, is the Internal
Ground Connection screw. This screw is identified by a ground symbol:
NOTE
Grounding the gauge case via threaded conduit connection may not provide
sufficient ground.
™
Radar Gauge
3
/ –14 NPT conduit connections.
4
.
2-23