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3. Electrical Connections
Caution: Failure to fully open terminal jaws before removing wire may permanently damage instrument.
Wiring Procedure
1. Remove 0.5 - 0.625 in. (13-16 mm) of insulation from wire end.
2. Press the orange terminal lever downward with a small screwdriver to open terminal jaws.
3. Insert exposed (non-insulated) wire end in terminal hole until it bottoms out.
4. Release orange terminal lever to secure wire in place. Gently pull on each wire to ensure a good connection.
Wiring Removal Procedure
1. Press the orange terminal lever downward with a small screwdriver to open terminal jaws.
2. When fully open, remove wire from terminal.
Terminals 1 and 2: Loop Power
12-24 VDC ±10% system power and current
loop output.
Max. loop impedance:
50 Ω max. @ 12 V
325 Ω max. @ 18 V
600 Ω max. @ 24 V
Internal open-collector
output circuit
15Ω
S
D
Isolation
Terminals 3 and 4: Open-collector Output
A transistor output, programmable in CALIBRATE menu as:
•
High or Low setpoint with adjustable hysteresis
•
Proportional pulse up to 400 pulses per minute
•
May be disabled (Off) if not used.
page 2 of 12
System Pwr
2
Loop -
System Pwr
1
Loop +
Output --
Output +
Terminals 9-12: Sensor connections
9-10 are mV (pH or ORP) input from the electrode.
11-12 are Temperature input from the electrode
4
Output -
3
Output +
Terminals 5-8: Preamplifier power and grounds
5-6 are DC voltages from the 8750 to power the
preamplifier.
7-8 are ground terminals for the sensor and for earth
ground.
Temp -
12
(WHITE)
Temp +
11
(GREEN)
Iso. GND
10
(BLUE)
mV Input
9
(BROWN)
Earth
8
GND
Sensr Gnd
7
(SHIELD)
V-
6
(BLACK)
V+
5
(RED)
‡ SIGNET 8750-1 pH/ORP Transmitter
2
1
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