ELECTRICAL CONNECTIONS
CAUTION: DO NOT EXCEED SPECIFIED SUPPLY VOLT-
AGE RATINGS. PERMANENT DAMAGE NOT COVERED
BY WARRANTY WILL RESULT. THIS UNIT IS NOT
DESIGNED FOR AC VOLTAGE OPERATION.
Electrical connections to the Series 605 Transmitter are
made to the two-screw terminal strip on the rear of the
case. Polarity is indicated by + and – signs stamped on
side. The schematic diagram of the Series 605 transmitter
is illustrated in Figure B.
in series with the current loop but in parallel with the receiv-
er input. Referring to Figure B, RLbecomes the 250 ohm
resistor and point X and Y are connected to the receiver
input, point X being positive (+) and point Y negative (–) or
ground. The resistor should be connected at the panel end
of the transmitter current loop close to the receiver input to
take advantage of the immunity of the current loop to elec-
trical noise pickup. Most electronic component distributors
stock a 249 r, 1/2 watt, ±1% tolerance metal film resistor
which is adequate for this application.
An external power supply delivering 10.0 to 35 VDC with a
minimum current capability of 40 milliamps must be used to
power the control loop in which the Series 605 transmitter
is connected. Refer to Fig. B for connection of the power
supply, transmitter and receiver. The range of appropriate
receiver load resistances (RL) for the power supply voltage
available is given by the formula and graph in Fig. C.
Shielded two wire cable is recommended for control loop
wiring and the negative side of the loop may be grounded
if desired. Note also that the receiver may be connected in
either the negative or positive side of the loop, whichever is
most convenient. Should polarity of the transmitter or
receiver be inadvertently reversed, the loop will not function
properly but no damage will be done to the transmitter.
SERIES 605
PRESSURE
TRANSMITTER
POWER
SUPPLY
10.0-35 VDC
RECEIVER (RL)
SEE FIG. C
NOTE: RECEIVER MAY BE IN
SERIES WITH + OR -
LEG OF CONTROL LOOP
The maximum length of connecting wire between the trans-
mitter and the receiver is a function of wire size and receiv-
er resistance. That portion of the total current loop resis-
tance represented by the resistance of the connecting wires
themselves should not exceed 10% of the receiver resis-
tance. For extremely long runs (over 1,000 feet), it is desir-
able to select receivers with higher resistances in order to
keep the size and cost of the connecting leads as low as
possible. In installations where the connecting run is no
more than 100 feet, connecting lead wire as small as No. 22
Ga. can be used.
The Series 605 transmitters can be used with receivers
requiring 1-5 volt input rather than 4-20 mA. If the receiver
requires a 1-5 volt input, insert a 250 ohm, 1/2 watt resistor
1400
1300
1200
1100
1000
900
800
700
600
500
400
300
200
100
05101520 25 30 35 40
RECEIVER RESISTANCE RL()
POWER SUPPLY VOLTAGE - VDC
RL MAX = VPS - 10.0V
20 mA DC
MAXIMUM VALUE (1250)
OPERATING
REGION
OUTPUT RANGING
Each Series 605 Magnehelic®indicating transmitter is fac-
tory calibrated to produce 4 mA at zero scale reading and
20 mA at full scale reading. The following procedure should
be used if the pressure versus output signal relationship
needs to be checked.
1. With unit connected to the companion receiver per pre-
ceding instructions, insert an accurate milliammeter
with a full scale reading of approximately 30 mA in
series with the current loop.
2. Vent both pressure ports to atmosphere and, if neces-
sary, adjust pointer zero screw to align pointer with zero
on scale. A controllable pressure source capable of
reaching the full scale range should be connected to
either high pressure port. Plug the other high pressure
port and vent one or both low pressure ports to atmos-
phere. The instrument must be ranged in the same
position in which it will be used. Standard factory cali-
bration and ranging is done with unit vertical.
3. Apply electrical power to the system and check for
proper operation by slowly increasing pressure and
observing whether the loop current increases above
the 4 mA zero pressure reading.
4. A spanner type key is supplied to adjust span and zero.
This helps to reduce unauthorized tampering. Apply
pressure until pointer aligns with full scale reading and
adjust the SPAN knob for a 20 mA reading.
Figure A
Figure B
Figure C
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