fs6611 Fortune Semiconductor Corporation, fs6611 Datasheet - Page 17

• Manufacturer Part Number: fs6611
• Description: Energy Metering Ic With Impulse Output
• Manufacturer: Fortune Semiconductor Corporation

Rev. 1.1
13.9 Selecting a Frequency for an Energy
As shown in Table II, the user can select one of four
frequencies. This frequency selection determines
the maximum frequency on F1 and F2. These
outputs are intended to be used to drive the energy
register (electromechanical or other). Since only four
different output frequencies can be selected, the
available frequency selection has been optimized for
a meter constant of 100imp/kWhr with a maximum
current of between 10A and 120A. Table V shows
the output frequency for several maximum currents
(I
meter constant is 100imp/kWhr.
The F
range of output frequencies on F1 and F2. When
designing an energy meter, the nominal design
voltage on Channel 2 (voltage) should be set to half
scale to allow for calibration of the meter constant.
The current channel should also be no more than
half scale when the meter sees maximum load. This
will allow over current signals and signals with high
crest factors to be accommodated. Table Ⅵ shows
the output frequency on F1 and F2 when both
analog inputs are half scale. The frequencies listed
in Table Ⅵ align very well with those listed in Table
Ⅴ for maximum load.
SCF S1
Table Ⅴ
Max
Table Ⅳ
1
0
1
0
1
0
1
0
) with a line voltage of 220V. In all cases the
1–4
I
Meter Application
Max
12.5
120
0
0
0
0
1
1
1
1
frequencies allow complete coverage of this
25
40
60
80
(A)
F1 and F2 Frequency at 100imp/kWhr
S0
Maximum Output Frequency on CF
0
0
1
1
0
0
1
1
13.6
13.6
(Hz)
F
1.7
1.7
3.4
3.4
6.8
6.8
1-4
F1 and F2 (Hz)
2048×F1, F2 = 5570
128×F1, F2 = 43.52
for AC Signals(Hz)
64×F1, F2 = 21.76
64×F1, F2 = 43.52
32×F1, F2 = 21.76
32×F1, F2 = 43.52
16×F1, F2 = 21.76
16×F1, F2 = 43.52
0.076
0.153
0.244
0.367
0.489
0.733
CF Max
AC Inputs
When selecting a suitable F
design, the frequency output at I
with a meter constant of 100imp/kWhr should be
compared with Column 4 of Table Ⅵ. The frequency
that is closest in Table Ⅵ will determine the best
choice of frequency (F
with a maximum current of 25A is being designed,
the output frequency on F1 and F2 with a meter
constant of 100imp/kWhr is 0.153Hz at 25A and
220V (from Table Ⅴ). Looking at Table Ⅵ , the
closest frequency to 0.153Hz in column four is
0.17Hz. Therefore, F2 (3.4Hz—see Table II) is
selected for this design.
13.9.1
Fig4 shows a timing diagram for the various
frequency outputs. The outputs F1 and F2 are the
low frequency outputs that can be used to directly
drive a stepper motor or electromechanical impulse
counter. The F1 and F2 outputs provide two
alternating low going pulses. The pulse width (t
set at 275ms and the time between the falling edges
of F1 and F2 (t
F1 (t
below 550ms (1.81Hz), the pulse width of F1 and F2
is set to half of their period. The maximum output
frequencies for F1 and F2 are shown in Table Ⅲ.
The high frequency CF output is intended to be used
for communications and calibration purposes. CF
produces a 90ms wide active high pulse (t
frequency proportional to active power. The CF
output frequencies are given in Table Ⅳ. As in the
case of F1 and F2, if the period of CF (t
180 ms, the CF pulse width is set to half the period.
For example, if the CF frequency is 20Hz, the CF
pulse width is 25ms.
Note:
When the high frequency mode is selected, (i.e., SCF = 0,
S1 = S0 = 1), the CF pulse width is fixed at 18µs. Therefore,
t4 will always be 18µs, regardless of the output frequency
on CF.
Table Ⅵ
S1 S0
0 0 1.7
0 1 3.4
1 0 6.8
1 1 13.6
2
). If, however, the period of F1 and F2 falls
Frequency Outputs
(Hz)
F
F1 and F2 Frequency with Half Scale
1-4
3
) is approximately half the period of
Frequency on F1 and F2 (Hz)
(Ch1 and Ch2 Half Scale AC
1–4
). For example, if a meter
1–4
Inputs)
frequency for a meter
0.085
0.17
0.34
0.68
Max
(maximum load)
5
) falls below
FS6611
4
) at a
1
17/20
) is