Watlow Series 1500 - Manual (Page 32)

How to Eliminate Noise
Watlow Part Number
for Quencharc:
0804-0147-0000
Call Watlow
Customer Service
for MOV Part
Number.
CAUTlON:
Whenever
attempting
to
open a Series
1500 with data
communications
(RS-422/423
interface), be
sure your
system’s DB-15
male connector is
not connected to
the rear of the
unit. The DB-l5
male connector
may be attached
to the 1500 with
two screws
through the rear
of the case to the
female DB-15
connector Inside.
Attempting to
remove the Series
1500 control
chassis from its
case with the DB-
15 male still
attached could
pull the circuit
board from its
chassis socket
1. Use “Quencharcs” to suppress noise generated by devices such as relays,
relay contacts, solenoids, motors, etc. A Quencharc is a simple filter
device using a .1µf, 600 volt, non-polar capacitor in series with a 100
ohm, 1/2 watt resistor. The device can be used on an A.C. circuit to
effectively dampen noise at its source. For a D.C. circuit, use a diodex
across the inductive load coil to dampen noise. This diode must be sized
to the coil, having a reverse voltage larger than the coil voltage. The
diode forward current must also be larger than the reverse coil current.
2. An “MOV’ (Metal Oxide Varistor) can be used to limit voltage “spikes” that occur
on the A.C. supply lines as a result of lightning strikes, switching large motors,
etc. The “MOV” is available in several varieties and for 115 or 230 volt lines. The
device dissipates the voltage “spikes” to ground and in doing so repeatedly,
deteriorates its ability to function. “MOV’s” have a limited life.
3. A “Corcom IERI” and other similar power line filters are designed to carry the
power for the control circuit and at the same time “buffed the control circuit from
A.C. line noise. Devices like a Corcom use media (electromagnetic filtering)
other than electric circuits to filter out the electrical noise. Care must be
taken in matching the power capabilities of the filter in respect to the power
demands of the circuit.
4. The ultimate protection is an “uninterrruptable” power supply. This device
“senses” the A.C. power line; when the line fluctuates, a battery-powered
60Hz inverted circuit takes over, supplying power within one-half to one cycle of
the A.C. line. This is a very expensive solution.
How to Open the 1500
Here’s how to open the Series 1500 and pull the control chassis from its case:
The control chassis fastens to the case with a single screw located at the lower front
panel. Turn the screw counterclockwise to loosen it. Three strip connector plugs, in
the rear of the control chassis, feed power and signals through the back of the case
to the triple terminal strip. These plugs will let go as you pull.
When removing the Series 1500 Control from its case, pull firmly but gently. When
returning the control to the case, be sure you have the top UP to match the boards
with the case plugs. The 1500 will not fit in to the case upside down. However,
always check to see that it is oriented correctly. Press the unit in firmly, then turn the
front panel screw clockwise to secure it. Do not overtighten screw.
Pre-Installation Information
The Watlow Series 1500 behind-bezel dimensions are 5.375 in. high by 5.375 in.
wide by 7.5 in. deep. The unit weighs 4.5 lbs. For dimensional and mounting
information, including the location of mounting holes and size of the front panel
cutout, see Figure 10.
The Series 1500 mounts on panels from 0.06 in. to 0.25 in. thick.
32
WATLOW Series 1500 User's Manual
Installation - Wiring Chapter 3