12
Model 4688-IR / 4679-IR
Operation & Maintenance Manual
Manual #087-0007G, 10/2003
Wiring and Power
Current Draw
Upon instrument start-up, the GasPlus-IR will experience a 500 mA transient
current draw. Immediately thereafter, current draw will drop to the
instrument's 250 mA i
MAX
, eventually "settling" down" to the 130 mA typical
current draw.
Maximum Wire Length
AWG wire size requirements are dependent upon power supply voltage and
wire length.
The maximum distance between the transmitter and its power supply is
determined by the maximum allowable interconnecting loop-voltage drop. If
the voltage drop is exceeded, the transmitter will not operate. To determine
the maximum loop-voltage drop, subtract the transmitter's minimum operating
voltage (18 VDC) from the power supply's minimum output voltage. For
example; if the power supply's minimum output voltage is 24 VDC, then the
maximum voltage drop across the power supply is 6 volts.
To determine actual maximum wire length, divide the maximum allowable
voltage drop by the transmitter's maximum current draw, then by the
resistance of the wire (ohms/foot), then divide by 2.
Switches and Circuit Breakers: UL and EN Requirements
EN 61010-1, 1995 edition and UL 3111-1, 1994 edition (Safety Requirements
for Electrical Equipment for Measurement, Control and Laboratory Use-Part 1:
General Requirements) contain the following requirement:
Except as specified in 6.12.1.1, equipment shall be provided with a means
for disconnecting it from each operating energy supply source, whether
external or internal to the equipment. The disconnecting means shall
disconnect all current-carrying conductors.
For the GasPlus-IR to comply with EN 61010-1, 1995 edition and UL 3111-1,
1994 edition:
1. A switch or circuit breaker must be included in the GasPlus-IR
installation,
2. The switch or circuit breaker must be in close proximity to the equipment
and within easy reach of the operator, and
3. The switch or circuit breaker must be marked as the disconnecting
device for the GasPlus-IR.
Minimum Operating Voltage
Power Supply Voltage
Max allowable volt drop (MAV)
(MAV ÷ Max Current draw)
÷ Ohms per ft
÷2
= Max Wire Length
Figure 4 -
Calculating
Maximum Wire
Length
VMIN Source Voltage
24 VDC
VMIN Transmitter
18 VDC
IMAX Transitter
250 m A
RMAX of W ire
24 Ohms
W ire Ohms/ft
Ma x Length Ft (M)
18 AW G (0.00639 Ohm /ft)
1878 (572)
20 AW G (0.01015 Ohm /ft)
1182 (360)
22 AW G (0.01614 Ohm /ft)
743 (227)
Sta nd-Alone 24 VDC Pow e r Supply
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
