Power wiring, Series 920 power wiring, Figure 15 – Watlow Series 920 Microprocessor-Based Ramping Control User Manual

Page 26

1 WARNING:

To avoid potential

electric shock, use

National Electric
Code safety prac-

tices when wiring

and connecting this

unit to a power

source and to

electrical sensors or

peripheral devices.

2 WARNING:

To avoid electric
shock, connect the

chassis ground

terminal to “Earth

Ground.”

Figure 15 -

Series 920 Power
Wiring.

CAUTION:

Remove the short
green ground

jumper on the back

of the 920 (T-21) if
your control is

mounted in a metal
panel connected to

safety (chassis)

ground. Removing
the jumper will

prevent ground

loops. OR
Leave the short

green ground

jumper in place if
the Series 920 case

is not connected to
safety (chassis)
ground.

Power Wiring

NOTE:

For

230VAC,

jumper 18 to

C h a s s i s

GND

Green

GND

Wire

3 WARNING:

Ground

NOTE:

For

115VAC,

jumper 17 to 19

and jumper l8 to 20

Ground

Disconnecting the green ground jumper wire could allow A.C. voltages to be

present on the metal case.

Connect the AC power lines and the jumper wires to the power supply terminal
strip of the Series 920. Study the strip connections carefully before beginning.

Be sure to use these jumpers on the power supply terminal strip. For 230VAC,

jumper 18 to 19. For 115VAC, jumper 17 to 19 and jumper 18 to 20.

All wiring and fusing should conform to the National Electric Code and to any

locally applicable codes also.

When you apply power without sensor inputs

on the Signal Conditioner termi-

nal strip, the Series 920 alternately flashes from SYSTEM to ERl 00XX. This
is an error code indicating an open sensor. These are normal displays for a

unit without sensors.

Before applying power, open the Series 920 and set DIP Switch #1 “ON” for a

Cold Start. Replace the control chassis in the enclosure and apply power to

the unit. (This clears all previously entered information from the 920; it is a

“clean” or “cold” start.)

Now remove power again, open the unit, and set the Switch #1 to OFF, (This

will make the next start a “warm” one, retaining all subsequently entered

information in the processor’s memory.) Close the 920.

WATLOW Series 920 User's Manual How to Install and Wire, Chapter 4