red lion PRA2 Manual

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MODEL PRA2 - PULSE RATE TO ANALOG CONVERTER

DESCRIPTION

The Model PRA2 is a convenient plug-in module that provides voltage and
current analog output signals proportional to the pulse-rate (frequency) of the
input signal. In typical applications the PRA2 input is supplied by a machine
mounted sensor that generates a signal which has a frequency proportional to
machine or process speed. The PRA2 converts the frequency content of this
signal to analog form for operating chart recorders, supplying speed control
signals, or driving other controls and indicators that require analog input.
The PRA2 develops an internal "constant-area" pulse from the negative
going edge of each input pulse or wave form cycle. These "Constant-area"
pulses are fixed in voltage amplitude and time duration. The PRA2 then takes
the average of a train of these pulses to generate an output voltage level
proportional to the frequency. Another circuit within the PRA2 monitors the
voltage output and produces a current output signal that will deliver either 0 to
1 or 4 to 20 mA, as determined by a set-up switch.
This unit is available with five overlapping adjustable range ratings, each
rating providing a calibration adjustment to deliver maximum output over an
input frequency range of approximately 3.3:1. Since the PRA2 develops an
output by averaging pulses, an inherent response time is involved (See response
table, next page). The minimum response time is fixed for each range rating. It
is longest for the lowest range rating and decreases as the frequency range rating
increases. Response time must be considered, when using the PRA2 to provide
closed-loop speed feedback signals, to avoid stability problems. For speed
feedback applications it is usually advisable to select a high frequency range
coupled with an appropriate sensor arrangement that delivers a high pulse rate.
The internal output filtering supplied for averaging purposes is kept to a
minimum to provide the fastest practical response time for each range rating.
Extra external capacitance can be added to provide more filtering if required.
DIMENSIONS In inches (mm)
2.37 (60.2)
* ZERO ADJUSTMENT (CURRENT OUTPUT ONLY)
* RANGE ADJUSTMENT (VOLTAGE & CURRENT OUTPUT)
1.77
(45.0)
SOCKET P/N 2300200
(22.4)
(ORDER SEPARATELY)
 DELIVERS ANALOG OUTPUT PROPORTIONAL TO INPUT
PULSE-RATE (FREQUENCY)
 ACCEPTS VARIABLE PULSE-RATE INPUTS FROM A WIDE
VARIETY OF SENSORS
 DUAL SIGNAL OUTPUT, 0 TO 10 VDC PLUS SELECTABLE
SIGNAL CURRENT OUTPUT OF 0 TO 1 MA OR 4 TO 20 MA
 SELECTABLE FREQUENCY RANGE RATINGS FROM 30 HZ TO
10 KHZ
 ACCURACY (LINEARITY) 0.25%
 SWITCH SELECTABLE FOR 115 OR 230 VAC
The plug-in module mates with a heavy duty, CSA approved base mounting
socket with pressure clamp screw terminals that accept stripped wires without lugs.

SPECIFICATIONS

1. PRIMARY SUPPLY VOLTAGE: Switch selectable for 115 or 230 VAC
±10%, 60 Hz; 8 VA
2. SENSOR OUTPUT POWER: +12 VDC ±5% regulated, 60 mA max.
3. SIGNAL INPUT CHARACTERISTICS: See "Input & Output Switch
Set-up" section.
4. MAX. FREQUENCY ADJUSTMENT: 30 Hz to 10 KHz
5. SIGNAL VOLTAGE OUTPUT: 0 to 10 VDC @ 10 mA max.
6. SIGNAL CURRENT OUTPUT (Selectable):
0 to 1 mA into load resistance range 0 to 4 K.
4 to 20 mA into load resistance range 0 to 250 
7. LINEARITY: ±0.25% of full range setting.
8. VOLTAGE/CURRENT OUTPUT TRACKING: Current Signals follow
voltage signals within ±3% of full range setting.
9. RESPONSE TIME: See table on next page.
10. OPERATING TEMPERATURE RANGE: 0 to 60
11. WEIGHT: PRA2 - 8 oz (226.8 g); Mating 12-Pin Socket - 2 oz (56.7 g).

ORDERING INFORMATION

MODEL NO. DESCRIPTION
PRA2 Pulse Rate to Analog Converter

Socket, 12-Pin
* 20 TURN SCREWDRIVER
ADJUSTMENTS ACCESSIBLE
THROUGH TOP
SOCKET
P/N 2300200
7
4.44
(112.8)
8
9
10
11
.88 12
2.31 (58.7)
1
Bulletin No. PRA2-C
Drawing No. LP0540
Released 10/12
o
C.
PART NUMBERS
.16 (4.1) DIA.
2 HOLES
6
5 .84
(21.3)
2.69
4
(68.3)
3
.84
(21.3)
2
1
PRA20000
2300200