Salinity Indicator Panel - Cont'd -141200411

(center) position and a TEST position. The rotary

switch, S1, when placed in the TEST position,

switch, s3, when placed in the TEST position,

disconnects resistor R5B in the salinity cell circuit,

connects the movable windings, A and B, of the

resulting in an unbalanced condition that causes the

power-factor-type meter in a circuit comprising

cell to behave as though a high salinity condition

resistor R10 and potentiometer R11, the resistances of

exists. This action energizes the alarm circuit, causing

which duplicate the resistances of the electrodes and

the red alarm light to flash and the alarm relay to sound

compensator. There are two circuits through the

the external alarm. The meter switch, S1, when placed

movable windings. One circuit is from line terminal

in the METER position, connects the meter unit in the

SB, the right arm of potentiometer R11, terminal 4 of

circuit of the associated salinity cell and a salinity

switch S3, resistor R10, to line terminal SBB. The

reading is indicated on the meter.

other circuit is from line terminal SB, the left arm of

VALVE POSITION AND METER TEST

potentiometer R11, terminal 6 of switch S3, resistor

UNIT.-- The valve position and meter test module

R10, to line terminal SBB. With the meter test switch

(fig. 10-42) is provided with a green valve position

in the TEST position, the meter should read 1.7 ppm.

indicator lamp and a meter test switch. The dual

RELAY UNIT.-- The relay module (fig. 10-42)

purpose of the unit is to indicate when the control

consists of an alarm relay, K2, and two 2-second delay

valve is in the NORMAL or ABNORMAL position

flashers. (For simplicity, only one flasher is shown.)

and to provide a means of testing the meter unit.

The flasher is used to delay the tripping time of the

When the solenoid trip valve is in the NORMAL

solenoid-operated valves. Normally, the current

position, as shown, the green indicator lamp is

through the delay flasher contact circuit is not

illuminated steadily; when the control valve is in the

sufficient to open the flasher contacts. However, if

ABNORMAL position, the green alarm light flashes;

terminal 5 of the relay unit is energized from an

and when the control valve is reset manually, the green

associated salinity cell, the flasher contact will open,

alarm light is again lighted steadily.

de-energizing control power relay K1-1 and causing

The meter test switch, when placed in the TEST

contacts K1-1 to open. This action de-energizes the

position, connects the meter unit in a circuit

valve control circuit, causing the valve to actuate.

simulating a known salinity condition (1.7 ppm) to

The rectifier, CR2, allows a current to flow

check the calibration of the meter.

through the operating coil of alarm relay K2, from the

The valve position portion of the unit consists of

plate of V1, through switch S2, in the NORMAL (up)

the green indicator lamp, I3, and the flasher, H1,

position, and back to the other side of line SBB.

interconnected with the solenoid-operated valve.

Rectifier CR5, across the coil of K2, maintains the

During normal operating conditions, the solenoid is

current flow through the coil during the non-

energized from the line terminal SSB through the

conducting half cycles of V1, The contacts of relay K2

contacts of the power control relay, K1-1, terminal 1

close to energize the external alarm circuit.

of the SPDT switch, S4 (on the control valve), to line

The silencing switch, S2, when placed in the

terminal SB. The green indicator lamp, I3, is

SILENT (down) position, opens the circuit to the

illuminated steadily during this condition from line

audible alarm and connects the plate of V1 to one side

terminal SB, the contact arm of flasher H1, to line

of the alarm light through CR2. As long as the salinity

terminal SBB.

is higher than the alarm setting, CR2 allows a current

When art abnormal condition occurs, the power

to flow directly through the red alarm light, 12, which

control relay, K1-1, is de-energized and its contact

is lighted steadily. During this condition, CR3

opens the circuit to the solenoid coil, which actuates

prevents a large current flow through the heater of the

switch S4. This action connects the heater and contact

flasher, H2, When the salinity decreases to a value at

arm flasher H1 from line terminal SB, through

which V1 ceases to conduct, the flasher heater voltage

terminal 2 of switch S4, to line terminal SBB, causing

causes the red indicator light to flash as a reminder for

the green indicator light to flash.

the operator to place the silencing switch, S2, in the

NORMAL (up) position.

The meter test portion of the unit consists of meter

test switch S3, resistor R10, and potentiometer R11.

Normally, the current flows through the relay

Normally, the meter unit is not connected to a salinity

module from the line terminal, SBB, the bimetallic

cell. The meter test switch, S3, is a two-position,

arm of the delay flasher, the coil of the power control

spring-loaded rotary switch having a NORMAL

relay, K1-1, to the line terminal, SB. This current

10-31