Manual

Schematics B–3
Publication 17716.5.99 - December 1995
Gate Inputs
Gate inputs are used for running prover and store count values.
Each gate is an electrically isolated circuit with a physical and
electrical isolation of 1500V ac. There is one gate associated with
each flowmeter input circuit (G0 corresponds to F0).
JPR 6 JPR 7
R4 R2
Q1
D3
D2
R79
R77
Voltage
Jumpers
D1
Input
RET
GO
G1
G2
G3
U12
+5V
C52
R87
G0
G1
G2
G3
physical and electrical isolation
1500V ac rms
gate jumpers:
JPR6 = ON for 1240V dc
JPR7 = ON for 512V dc
E11 E11 E11
R1
C51
C55
7
29
31
GO
G1
G2
G3
8
30
32
5
6
external device
470 470
330
To turn on a gate circuit, you must source current through the input
resistors sufficient to turn on the opto-isolator in the circuit. If no
connection is made to the pair of gate terminals, no current will flow
through the photodiode of the opto-isolator and that gate will be OFF
(the corresponding input status indicator is OFF).
The input current magnitude can be determined by the state of the
gate jumper:
CASE A  gate jumper set for 512V dc operation (JPR 7 is ON)
gate input current = (gate input voltage - 2V
)
330
gate input current = (gate input voltage - 2V
)
1270
If gate input voltage = 40V dc
gate input current = (40V - 2V)
1270
gate input current = 30mA
If gate input voltage = 5V dc
gate input current = (12V - 2V)
1270
gate input current = 8mA
Examples
If gate input voltage = 12V dc
gate input current = (12V - 2V)
330
gate input current = 30mA
If gate input voltage = 5V dc
gate input current = (5V - 2V)
330
gate input current = 9mA
Examples
CASE B  gate jumper is set for 1240V dc operation (JPR 6 is ON)
There is approximately a 2V drop across (Q1 + the photodiode).
The operating range of the input is 510mA and Q1 functions as an overcurrent
protection circuit. If an open collector device with pullup is used, the value of
the pullup must be added to the
value shown in the denominator
.