Liquid Controls SP2900 - Manual (Page 13)

APPLICATION
The unit monitors the power consumption and transmits the
rate, total or grand total usage upon command to a printer,
PLC or computer. Either control Relay A or Relay B can be
activated by rate, total or grand total readings. If Relay A is
set for rate, it can activate an alarm for load management if
the preset usage is exceeded. Relay B can be set to
activate at any rate, total or grand total alarm setting. The
customer has it his way when selecting the external de-
vices to record the unit data. A frequency selectable pulse
output can drive any totalizer, PLC, computer or other pulse
input device from 10 to 20,000 Hz. With the analog output
option the customer keys in both the 4mA and 20mA rate
settings and the unit drives the strip chart recorder, load
shedding or other monitor devices. Finally, with the RS232/
RS422 or RS422M option the customer can have a printer
record any data or have a computer communicate with up
to 256 units to monitor the usage, change alarm points,
reset the internal counters, etc. from a remote location.
MOUNTING DIMENSION
Dimensions are in inches (mm)
PULSE INPUTS
The unit accepts output pulses from most encoders, prox.
switches or contactors. Connect the pulse to Input A Pin 4.
The unit counts on the negative edge of a pulse: Low: 0 to
1 VDC, High: 3 to 30 VDC.
SOURCING INPUT - Has a 10K Ohm pull down resistor to
ground and must be driven high by a sourcing device such
as a PNP transistor or a contact to +DC, Pin 13.
SINKING INPUT- Has a 4.7K Ohm resistor to +12 VDC
and must be driven low by a sinking device such as a NPN
transistor or a contact to ground (Pin 12).
PULSE SPEED
The Max input speed is specified by the 8th digit of the part
number based on a 50% on/off pulse. Although the unit
can accept pulses as short as 25 usec on/off if speed “E” is
selected, it is advised that only the maximum speed
needed be ordered. When lower speeds are specified,
additional filtering is added that make the inputs more
immune to electrical noise. “A” input speed should always
be used when pulsing with a switch contact to prevent
additional erratic count inputs.
INPUT SWITCH SELECTION
Inputs use an input signal conditioning board which is
plugged onto the main board just behind the display. It has
dip switches which set the debounce filtering (max. count
speed). (See section for “Removing Case” to get to the
input modules if changes on the pulse input board are
needed.)
S1, S2 determine debounce filtering and control max. input
speed,
(A) S1, S2-ON, 0-40 Hz (min. 12.5 msec on/off)
(C) S1-ON, S2-OFF, 0400 Hz (min. 1.25 msec on/off)
(E) S1, S2-OFF, 0-20K Hz (min. 25 usec on/off)
S3, S4 set the input characteristics as designated by the
5th and 6th digits of the part number.
SOURCING INPUT: S3, S4-OFF (needs sourcing input)
SINKING INPUT: S3-OFF, S4-ON (needs sinking input)
ANALOG INPUTS
The analog input versions accept signals from transmitters
that give linear outputs. The input signal modules are
mounted just behind the display and are calibrated for the
input specified. Insure that the sensor output matches the
unit input. Connect the analog signal to input A (Pin 4) with
the return to ground (Pin 12).
SQUARE LAW: 4-20mA; 250
Ω
input impedance, the
square law input is a special input that compensates for
non-linear inputs. Specifically, inputs that require square
root extraction to provide accurate count and rate determi-
nations. The input signal is converted to 0 to 10,000 pulses
per second input to the process (see Table below).
A B C D
1 2 3
4 5 6
7 8 9
CLR 0 SET
8.170
(207.5)
3.305
(83.9)
.525
(13.3)
6.000
(152.4)
2.480
(62.9)
PANEL
CUTOUT
2.496 ± .010
(187.0 ± .25)
7.365 ± .010
(187.0 ± .25)
7.055
(179.2)
7.349
(186.7)
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