OPTIONS
1/2 EMT Conduit Fitting
1/2 NPT Pipe Fitting
Relay-Track Mounting Adapters
External Explosion-Proof Housing
Companion Current Transmitters
DESCRIPTION
Model 508B is a two-wire current-loop indicator that is powered directly
by a 1-5 mA, 4-20 mA or 10-50 mA process loop signal, with a maximum
voltage drop of 2.5 V. No separate power supply connections are required.
This reduces overall hardware and field wiring costs and provides
immunity from most electrical noise encountered in process control
environments. The electronics are isolated from the case.
READOUT OF PROCESS VARIABLES
The 508B provides extensive zero and span adjustment capability, so
that it can read out directly in percent or in engineering units for
process variables such as pressure, flow, temperature, or level. Its
liquid crystal display provides 3 1/2 active digits, a selectable
dummy right-hand zero, and four programmable decimal points. By changing
two internal jumpers, the normal positive slope response of the 508B
can be reversed, so that increasing the input decreases the reading.
EASY TO CONFIGURE AND CALIBRATE
Both span and zero are fine-tuned with precision multiturn potentiometers.
These are accessible through holes in the die-cast cover, which are
normally sealed with fluorosilicone plugs. Coarse zero and span steps
are selected by removing the cover with attached electronics and changing
plug-in jumpers.
DESIGNED FOR HARSH ENVIRONMENTS
All versions of the 508B are rated for operation from –40 to +85°C
(–40 to +185°F) with specified accuracy. The case is made of die-cast
metal and is waterproof to 35 kPa (5 psi). The electronics are firmly
connected to the case top, so that the meter can withstand high vibration
and shock. Mounting options include a male 1/2 EMT conduit fitting
and a male 1/2 NPT pipe fitting in lieu of the normal rail or surface
mount. These fittings eliminate the external screw terminals and provide
a NEMA-4X rating.
INTRINSIC SAFETY CERTIFICATION
FM intrinsic safety certification is standard. Intrinsic safety certification
allows the 508B to be used in worst-case hazardous environments with
no need for an explosion-proof housing, provided that an intrinsic
safety barrier is used to limit the voltage and current that may be
introduced in the hazardous environment.
FM certification (USA) is for Class I, II, III, Division 1, Groups
A, B, C, D, E, F, G. The FM certification number is 5X2A0.AX (3610).
EXPLOSION-PROOF HOUSING OPTIONS
Two external
NEMA-7 explosion-proof and NEMA-4 waterproof, sand-cast, copper-free
aluminum enclosures with corrosion resistance "safety-blue"
polyester powder-coating for use in hazardous locations.
FM, UL, cUL Certification: Class I, Groups B, C, D; Class II, Groups
E, F, G; and Class III, Type 4X.
Demko/ATEX Certification: Ex II 2 G D EEx d IIC
Option EPW3 is a single-height enclosure for one 508B loop-powered
indicator.
Option EPW2 is a double-height enclosure for a 508B loop-powered indicator
on top and a 500 Series isolated two-wire 4-20 mA transmitter on the
bottom for indicating transmitter applications.
Available with two female 1/2 NPT pipe fittings, all required internal
mounting hardware, and mounting flanges for a wall or bulkhead.
SPECIFICATIONS
INPUT
Signal: 1-5 mA, 4-20 mA or 10-50 mA (jumper-selectable)
Linear Range: 0.3 to 50 mA
Protection: Up to 200 mA forward, 1000 mA reverse
Forward voltage drop, max: 2.5 V up to 50 mA
Input Resistance: 50 ohm at 1-5 mA, 12.5 ohm at 4-20 mA, 5
ohm at 10-50 mA
Zero Adjust: –2,000 to +2,000 counts (4 jumper- selectable
ranges plus fine adjustment)
Span Adjust: 0 to 2,000 counts with fine adjustment
NMR: 46 dB, 50/60 Hz
CMR: (meter to case) 120 dB, DC to 60 Hz
CMV: (meter to case) 700 Vp
RFI Susceptibility: Less than ±0.5% of span with conduit fitting
or external explosion-proof housing in 10V/m field strength at 27
or 440 MHz
ACCURACY AT 25°C
Maximum Error: 0.1% of span ±1 count 00 Zero tempco ±0.1 count/°C
typical, ±0.2 count/°C max
Span Tempco: ±0.005% of span/°C typical, ±0.015% of span/°C
max
ANALOG-TO-DIGITAL CONVERSION
Technique: Dual-slope, average-value
Polarity: Automatic
Integration Period: 100 msec
Read Rate: 2.5/sec
DISPLAY
Type: 7-segment, LED
Height: 0.35" (8.9 mm)
Symbols: –1.8.8.8.0 (3 1/2 active digits plus one jumper-selectable
dummy right-hand zero)
Decimal Points: Four positions, jumper-selectable
Overrange Indication: Three least-significant active digits
blank
ENVIRONMENTAL
Operating Temperature: –40 to +85°C (–40 to +185°F)
Vibration: 0.06" (1.52 mm) double-amplitude cycled at 10-80
Hz
Shock: 55 g half-sine, 9-13 ms duration
Waterproof Pressure: 35 kPa max (5 psi)
MECHANICAL
Diameter: 2.9" (74 mm)
Height, Including Barrier: 1.9" (48 mm)
Weight: 14oz (400 g)
ELECTRICAL CONNECTIONS
508B-1: 3-terminal barrier strip with #6 screws
508B-2: 1/2" EMT male conduit fitting with two 0.3 meter #18
stranded wires
508B-3: 1/2" NPT male pipe fitting with two 0.3 meter #18 stranded
wires
