Watlow Series 985 - Manual (Page 9)

"Islatros" and other similar power line filters are designed to carry the power
for the control circuit and “buffer” the control circuit from A.C. line noise.
Devices like the lslatrol use media (electromagnetic filtering) other than
electric circuits to filter out electrical noise. Take care in matching the power
capabilities of the filter with power demands of the circuit. Keep line filters as
close to the control as possible to minimize the area for interference pick up.
lslatrols are available from: Control Concepts Corporation
328 Water Street
P.O. Box 1360
Blnghamton, NY 139O2-1360
Phone: 607/724-2464
I - 101 (1A,l20VAC) I - 202 (2.5A, 208/240VAC)
I - 105 (5A, 120VAC) I - 207 (7.5A, 208/240VAC)
I - 115 (15A, 120VAC)
The ultimate protection is an “uninterruptable” power supply. This 'senses'
the A.C. power line; when the line fluctuates, a battery powered 6OHz in-
verted circuit takes over, supplying power within one-half to one cycle of the
A.C. line; very expensive.
How To Check For Ground Loops
To check for ground loops, disconnect the ground wire at the ground termina-
tion. Measure the resistance from the wire to the point where it was connected.
The ohmmeter should read a high ohm value. If you have a low ohm value
across this gap, there is at least one ground loop present in your system.
Or check for continuity; your reading should be "open”. If you do find continu-
ity, you must now begin looking for the ground loops. Begin disconnecting
grounds in the system one at a time, checking for continuity after each discon-
nection. When continuity reads "open” you have eliminated the ground loop(s).
Also, as you reconnect grounds, keep making the continuity test. It is possible
to reconnect a ground loop.
Noise Suppression Devices Available From Watlow
Watlow Controls stocks a few key noise suppression parts. You may order
these by calling your
local Watlow distributor.
Item Electrical Ratlngs Part Number
Common Mode Line Filter 25OV, 3 Amp 0804-0196-0000
Differential Mode Line Filter Refer to the lslatrol listing above.
Metal Oxide Varistor 15OV, 80 Joule 0802-0273-0000
MOV 13OV,38 Joule 0802-0304-0000
MOV 275V, 75 Joule 0802-0266-0000
MOV 275V, 140 Joule 0802-0405-0000
Table 1 -
NoiseSuppressIon
Device Ratings
Install and Wire, Chapter 2
WATLOW Series 98O/985 User’s Manual 9