Watlow Series 922 - Manual (Page 21)

How to Install and Wire, Chapter 4 21 WATLOW Series 922 User's Manual
This chapter tells you how to install the Series 922. All mounting and wiring
information is right here. Because Watlow controls are thoroughly tested, and
"burned in" before leaving the factory, the Series 922 is ready to install when you
receive it.
But before you begin working or cutting holes in panels, read through this
chapter to gain an understanding of the entire installation. Consider sensor
installation carefully. You'll need to look at the noise reduction guidelines before
making your panel cutout.
Miscellaneous Sensor Information
Temp - RH
Wet Bulb/Dry Bulb - In this 922 configuration, a dry bulb RTD measures tem-
perature on Channel 1. A wet bulb RTD, in combination with the dry bulb RTD,
senses relative humidity on Channel 2. The 922 calculates the temperature
difference between the two bulbs to determine per cent relative humidity.
The humidity/dehumidify outputs (Outputs 3 & 4) are disabled when the Channel
1 temperature falls below 32
°
F/0
°
C, or goes above 212
°
F/160
°
C. The RH display
reads OFF, and the retransmit output is 0 (volts) if ANLG = C2. ANLG is located
in the Setup menu under Access (5).
Solid State - RH Sensor
Vaisala Model HMM 30C Relative Humidity Sensor - With the Vaisala configu-
ration, Channel 1 must be configured to measure temperature, and Channel 2
must be a process input configured for humidity with the Vaisala sensor. See
below for the TYP parameter description. This parameter is located in the Setup
menu, under Access (5). DIP switch #4 must be set to the ON position. The
humidity and dehumidify outputs (Outputs 3 & 4) are disabled when the Channel 1
temperature falls below -40
°
F/-40
°
C or goes above 320
°
F/160
°
C. The RH display
will read OFF and the retransmit output is 0 (volts) if ANLG = C2. ANLG is
located in the Setup menu under Access (5).
Temp - Temp
For Temp-Temp RTD operation, each dry bulb RTD or thermocouple senses
temperature for its channel.
RTDs
The RTDs for the Series 922 are customer-supplied items. They may be Gordon
Part #S001-0133-0000, which is a wire-wound RTD inside a sealed, 18% Nickel-
Silver sheath, made for fast temperature response. The detector element is
platinum wire 100
Ω
at 0
°
C with a temperature coefficient of 0.003916
Ω
/
Ω
/
°
C. The
sheath is 0.1875 in. (4.7625mm)diameter, 2.75 in. (69.85mm) long. The three
wire leads are 48 in. (1219.2mm) long and teflon insulated.
NOTE: The dry bulb
and wet bulb sensor
should be mounted
in the same location.
However, do not
locate the wet bulb
ahead of the dry
bulb in the air
stream, this could
cause incorrect
relative humidity
readings.
Chapter 4
How to Install and Wire the Series 922
Install/Wire