Flowserve 90 Series Controller - Manual

Worcester Controls
WCAIM2045
(Part 18478)
Positioner/Controller for Series 90
Modular Accessory System
Installation, Operation and Maintenance Instructions
The Worcester/McCANNA M.A.S. positioner/controller circuit board is
designed for use with the Worcester/McCANNA Series 90 Modular
Accessory System.
For M.A.S. housing assembly, installation, and maintenance
instructions, refer to Installation, Operation and Maintenance Manual
Part WCAIM2005.
Note: A spring-return or double-acting type solenoid block
(corresponding to the type of 39 actuator) is required for operation of
the Positioner/controller.
1.Important:
PLEASE READ THIS SECTION
a. The AC M.A.S. positioner/controller board 4-20 mA signal input
circuit is protected with a 62 mA fuse (F1) installed across the
input circuit. Earlier versions also used a 12-volt zener diode.
This is to protect the CMOS chip from both an overvoltage
condition and reverse polarity of the input signal. The signal
input impedance of the circuit board is approximately 220 ohms
which means that it only takes about 4.5 volts to drive 20 mA
through the input circuit. If your current source is capable of
outputting 12 volts or more, it may be necessary to place a
Z\v
watt resistor in series with the current loop to drop the excess
voltage, otherwise you might find that you keep blowing the
input protection fuse. This is most likely to happen when you
initially turn on your current source, i.e., before it starts
regulating its output current. For example, let’s say you measure
an open circuit voltage from your current source of 24 volts.
Apply the following formula to determine the value of the resistor
to be added in series with the current loop:
R = [24 volts - (.05 x 220 ohms)] /.05
This calculation may yield a resistor value that is not a common
standard value. Select a resistor of the next higher standard value
(i.e., if your calculation result is a value of 260 ohms as in the
above example, then pick the next higher standard resistor value
which in this case would be 270 ohms). This will ensure that
enough voltage will get dropped across the added resistor at
50 mA, to prevent the zener diode from turning on and causing
the fuse to blow. If there are other devices in the current loop
such as a chart recorder or digital readout, then its input
resistance must be added to the input resistance of the circuit
board (in the above formula, 220 ohms would be replaced by the
total loop resistance). If the calculation results in a zero or a
negative resistance value, then no additional series resistor is
needed. The fuse used in the input circuit of the AC version is a
Littlefuse PICO II very fast-acting fuse rated at 62 mA (Newark
part number 94F2146). There is a spare fuse located on the
circuit board in the area of the input circuit fuse.
b. The DC version of the M.A.S. positioner/controller board has a
power supply fuse (F1) only. This is a 1 amp glass body fuse
(Littlefuse 2AG subminiature fast-acting fuse, .177" diameter x
.57" long) used to protect the circuit board in the event of a
component failure or the application of an over-voltage or voltage
of the incorrect polarity.
CAUTION: It is important that the power source be connected
properly to the M.A.S. terminal strip. This terminal strip is the
one located next to the solenoid block assembly. Terminal “A”
of this strip is to have the negative or neutral wire connected to
it. Terminal “B” is to have the positive or hot wire connected to
it. The board has a diode and a fuse installed to prevent
damage, as in the case of reverse voltage polarity, but if the
diode happens to be defective, the damage could be done
before the fuse blows.
c. The M.A.S. positioner/controller board has been designed to
receive a floating current input signal as the standard setup from
the factory. This allows several pieces of equipment to be operated
from the same current loop while at the same time remaining
electrically independent of each other. A floating input signal
means that the current input signal should not be referenced to the
circuit board ground. This is especially important with DC powered
circuit boards. The board power source must have a ground
independent from that of the signal source.