Dwyer SCS - Manual (Page 2)

©Copyright 2008 Dwyer Instruments, Inc. Printed in U.S.A. 12/08 FR# R6-443696-00
DWYER INSTRUMENTS, INC.
Phone: 219/879-8000 www.dwyer-inst.com
P.O. BOX 373 • MICHIGAN CITY, INDIANA 46361, U.S.A. Fax: 219/872-9057 e-mail: [email protected]
MAINTENANCE
Upon final installation of the Series SCS Current Switches, no routine
maintenance is required. A periodic check of system calibration is
recommended. The Series SCS is not field serviceable and should be
returned if repair is needed (field repair should not be attempted and may
void warranty). Be sure to include a brief description of the problem plus
any relevant application notes. Contact customer service to receive a
return goods authorization number before shipping.
TROUBLESHOOTING
Symptom
Series SCS solid
state output does
not function
Set point screw
keeps turning
Motor is turned on
and switch does
not close
Action
Verify that the maximum amperage range has not
been exceeded. Voltages or currents above the
rated levels may damage the Series SCS.
The set point screw has a slip clutch to prevent
damage at either end. To return the LED to its
original setting, turn the set point screw 20 full
turns counterclockwise and start the calibration
procedure again.
Insufficient current to the load leads (for example a
motor or heater) to reach the set point threshold.
To turn switch on, wrap the cable multiple times
through the sensing hole (see Figure 5).
2. Slowly turn the set point screw clockwise until the Status Closed LED
turns off and the Status Open LED turns on.
3. Turn the setpoint screw an additional 1/4 turn clockwise to create a
deadband to prevent hunting.
The Series SCS is now calibrated to signal current flows above normal full
load amperes.
Output status:
• Normal: Output Open
• Alarm: Output Closed
STATUS STATUS
OPEN SETPOINT CLOSED
FIGURE 10
STATUS STATUS
OPEN SETPOINT CLOSED
FIGURE 9
STATUS STATUS
OPEN SETPOINT CLOSED
FIGURE 8
3. Turn the setpoint screw an additional 1/4 turn counterclockwise to
create a deadband to prevent hunting.
The Series SCS is now calibrated to signal current flows below normal full
load amperes.
Output Status:
• Normal: Output Closed
• Alarm: Output Open
Over Current Status Condition (Locked Roter, Seized Impeller):
1. Turn the set point screw counterclockwise until the Status Open LED
turns off and the Status Closed LED turns on.
Note: This is the default factory setting.
2. Slowly turn the setpoint screw counterclockwise until the Status Closed
LED turns on and the Status Open LED turns off.
STATUS STATUS
OPEN SETPOINT CLOSED
FIGURE 7
SET POINT CALIBRATION (For Adjustable Models Only)
Position the Series SCS such that the status output panel faces you.
Confirm the monitored load (for example, a motor or heater) is running, and
then use the following methods to calibrate the Series SCS.
Under Current Status Condition (Belt Loss, Coupling Shear, Fan,
and Pump Status):
1. Turn the setpoint screw clockwise until the Status Closed Light-Emitting
Diode (LED) turns off and the Status Open LED turns on.
CURRENT > 135 A
FIGURE 6: SERIES SCS
WITH CT TRANSFORMER
FIGURE 5: SERIES SCS SHOWN
WITH FOUR TURNS
Failure to derate the current capacity could result in damage to the Series
SCS when using multiple turns to increase the measured current. Use the
following formula to determine the new maximum current:
New maximum current = SCS current rating / number of turns
For example, Model SCS-211125 with 4 turns = 135 A / 4 = 33.8 A, new
maximum current.
If measured current is above ratings of the switch:
Use a 5 A Current Transformer (CT) to reduce the current passing through
the SCS as shown in figure 6. Run the current transformer secondary wire
through the sensing hole. Terminate the 2 secondary wires of the 5 A
current transformer to each other, and then install the 5 A current
transformer on the monitored conductor.
NOTICE
INCREASING/DECREASING MEASURED CURRENT
If the measured current is too low to be detected or is higher than the
maximum current rating of the SCS, use the following methods to increase
or decrease current.
If measured current is too low to be detected:
Wrap the conductor (wire) through the sensing hole and around the SCS
body to produce multiple turns to increase the measured current. Use the
below equation to determine how many wraps are necessary:
Measured current = actual current times the number of turns. (See figure 5).
CONTACTOR
DO
DI
24 V AC/DC
RELAY COIL
FAN OR PUMP
CONTROL
POWER
120 VAC
FIGURE 4
PC-1-SCS:TEMPLATE 12/4/08 2:15 PM Page 2