500 Series Isolated 4-20 mA Transmitters

	The 501 transmitter is designed for 3-wire RTD operation, which compensates for lead resistance. The +S terminal is not connected internally. Shorting the -S and -EXC terminals provides 2-wire operation.
	The 502 utilizes the power-supply leads as signal leads. This simplifies field wiring by eliminating separate power and signal leads.
	The 505 can be used as a 4-20 mA current loop isolator. The input and output loops are each powered by their own supply.

Adding Digital Panel Meters to a 4-20 mA Loop
One or more digital panel meters may be added to a 4-20 mA loop for local readout in percent or engineering units, without degrading the accuracy of the 4-20 mA signal. NEWPORT"s 508B and 558B loop-powered indicators derive all operating power from the loop itself, with a maximum loop drop of 2.5 V. The use of such indicators simplifies field wiring. NEWPORT's INFINITY^® meters insert a loop resistance of only 15 ohm for a maximum loop drop of 0.1 V at 20 mA. INFINITY^® meters are available with dual or quad relay output for control or alarm.

Powering the 4-20 mA Loop and the Transmitter with a Low-Cost Meter A Model IDP, INFCP (3 1/2 digits) or INFP, 200B-E (6 digit) panel meter may be used to power the 4-20 mA loop, including the isolated 2-wire transmitter. One of more loads may be added to the loop, including receiving equipment in the control room. The excitation supply is electronically floating, so that the current loop may be grounded anywhere. In addition to powering the loop, the panel meter provides a local display scaled in percent or in engineering units.

EPW3 (w/window), EPH1 (wo/window), and Double-Height Lid

External Explosion-proof Housings
Left: EPW3 (with window) for one 508B loop-powered indicator.
Right: EPH1 (without window) for one 500 Series transmitter.
Center: Double-height lid (with window) supplied with EPW2, which is for one 500 Series transmitter (on bottom) and one 508B loop-powered indicator (on top).

Transmitter clamped to DIN Relay rack/Snap rack

Rail mounting of 500 Series transmitters
Left: Transmitter clamped to DIN relay track. A MDT1 adapter is required.
Right: Transmitter clamped to snap track. The standard housing fits 2.50" (63.5 mm) width. A MAT1 adapter is required for 2.75" (69.9 mm) or 3.00" (76.2 mm) width.

MOUNTING METHODS
1. Surface mount with four #6 rear-entry screws. Tapped holes are provided in back of case. Screws are inserted from backside of bulkhead.
2. Snap mount into 2.50" (63.5 mm) relay track.
3. Surface mount with two #8 front-entry screws. Requires optional MAT1 adapter plate.
4. Snap mount into 2.75" (69.9 mm) or 3.00" (76.2 mm) relay track. Requires optional MAT1 adapter plate.
5. Snap mount into DIN relay track per CENELEC standard EN 50 022. Requires optional MDT1 rail clamp.
6. Push mount into optional external waterproof or explosion-proof housings EPH1 or EPW2. Includes MXS1 spring retainers.

THREE TRANSMITTER STRATEGIES
A. The 4-20 mA signal is transmitted directly to the control room, without local readout or alarm.
B. Local readout is provided by process indicators in series with the 4-20 mA current loop. The two models shown are loop-powered, with no need for external power. Local readout, alarm and control could also have been provided by an INFINITY^® meter/controller in series with the 4-20 mA loop.
C. The 4-20 mA transmitter signal as well as local readout, alarm and control are provided by INFINITY^® with no need for a separate transmitter.

3 Transmitter Strategies