Ametek DPA1 Series Installation, Operation And Troubleshooting Instructions page 16

Installation
If it is desired not to construct the suggested dummy load, a load should be selected that will
not exceed the full rated current output of the unit at full rated output Voltage. The operational
load could be used.
transformer while setting the Gain and Bias controls.
d. Establish the proper resistance of the control signal input to the Firing Circuit as follows:
(1) Determine the rated current output of the process controller to be used. Usually the value
will fall into one of three ranges. A specific input resistance is required for each range.
Table 2-1 lists the maximum output current ranges of the controllers and the associated
input resistance.
Table 2-1 Controller Output Current VS. Control Signal Input Resistance
RATED CONTROLLER
OUTPUT CURRENT (MA)
0 To 12
12 To 30
30 To 50
2) Using a Simpson 260 multimeter or equivalent, measure the resistance between
terminals 1 and 2 on terminal strip TB1. See figure 2-1.
3) The resistance measured should be +20 percent of the value required in Table 2-1 for
the maximum current output of the process controller.
4) If the resistance measured in step (3) is not as specified, shunt terminals 1 and 2 on
terminal strip TB1 with one watt resistors until the ohmmeter does indicate the
specified value of input resistance. Unless otherwise requested, the units are shipped
with a 1500-Ohm input resistance.
5) When the shunt resistor is found that establishes the required input resistance,
terminate each lead of the resistor with an insulated spade lug.
6) Disconnect the ohmmeter and connect the resistor between terminals 1 and 2 terminal
strip TB1.
7) This completes the procedure for establishing the input resistance of the control
signal.
e. Connect the positive (+) lead of a low resistance DC milliammeter to terminal 1on terminal strip TB1. A
Simpson 260 multimeter or equivalent may be used for this purpose.
f. Connect the negative (-) lead of the DC milliammeter to the negative (-) terminal on the process controller.
The process controller should be adjusted to manufacturer's specifications.
g. Connect the positive (+) terminal of the process controller to terminal 2 on terminal strip TB1. At this point,
the milliammeter is connected to measure the control signal current from the process controller.
10
CAUTION
If the unit has current limit, do not put a wire through the current
REQUIRED CONTROL
SIGNAL INPUT
RESISTANCE (OHMS)
1500
500
300
AMETEK HDR Power Systems
Phase/AMP Series DPA1/DCPA1
SHUNT RESISTOR
REQUIRED
NONE
750 OHMS, 1 Watt
330 OHMS, 1 Watt
Document 9100030