Hoffman Controls 905 Series Manual
Installation
1. Remove all power to the control cabinet and load.
2. Disconnect wiring to 900 Series Power Switch.
3. Remove heatsink mounting hardware and remove
900 Series Power Switch.
4. Cut new rectangular access hole 2.0" wide by 4.5"
high. This hole should be centered around the
existing circular hole from the 900 Series Power
Switch. Clean and de-burr edges as needed.
5. Install the 905 Series Power Switch and secure it
with the hardware removed in #3 above.
6. Re-establish load wiring as previously configured to
the RED / BLK line voltage connections.
7. Connect the W1(+) control signal of the 905 Series
Power Switch to the 24VAC OUT 4 terminal of
the 901-D Series Logic.
8. Connect the W2(-) control signal of the 905 Series
Power Switch to the 24VAC OUT 3 terminal of
the 901-D Series Logic.
9. Refer to Figure 1 for determining control signal
connection points on 901-D Series Logic.
10. Restore power and prepare for checkout with your
desired input to the 901-D Series Logic.
Checkout
When retrofitting an existing 900 Series Power Switch,
the 901-D/DP and signal source are assumed to be
functioning normally. Checkout consists of generat-
ing demand with the signal source and verifying 905
Power Switch operation via it's indicator led or moni-
toring the load.
For complete re-calibration instructions (if required)
refer to HCC Document #176-0171-000, 901-D and
901-DP Recalibration Procedures.
General
The 905 Series Power Switch is the recommended
replacement for the previous 900 Series of single phase
power switches being controlled by Hoffman Controls
901-D/DP Series Logic.
Three models are available to accommodate all line
voltage applications: 905-120/277, 905-347/480, and
905-600. All units are capable of handling line currents
up to 48 Amps in capacity.
The 905 Series Power Switch also includes an
optional Thermal Cut Out control. The power switch
temperature is monitored and the unit safely disabled
if temperatures exceed rated limits.
900 Series Upgrade
The 905 Series Power Switch is 100 % electrically
compatible with the 900 Series Power Switch in that
both units utilize a simple 4 wire flying lead connection
scheme. There are 2 power leads to connect the switch
in series with the load, and 2 signal leads to activate the
power switch. The required connections are shown in
Figure 1.
Connections for the 900 Series Power Switch are pres-
ent at the end of an electronics tube that protruded into
the control cabinet through an approximately 2.0" diam-
eter hole. The 905 Series Power Switch has eliminated
the need for this space consuming configuration.
A new rectangular cutout will be required in the con-
trol cabinet to access the lower profile connections and
provide appropriate clearance of terminals. A full size
mounting template for accommodating the 905 Series
Power Switch is shown in Figure 2.
While a new cutout is required for the 905 Series
Power Switch connections, the heatsink mounting holes
utilized for the 900 Series Power Switch product will be
suitable for the 905 Series Power Switch product. The
905 Series Power Switch product will continue to mount
vertically to the external surface of the control cabinet for
ventilation.
The depth of the heatsink protrusion on the back
panel of the control cabinet has not changed and remains
approximately 3.0".
The 905 Series heatsink is 1.0" taller / longer than that
of the 900 Series Power Switch (5.0" vs. 4.0" respective-
ly), and may require additional clearance on the outside
of the control cabinet.
Hoffman|Controls
Installation & Operating
Instructions
905 Series
Single Phase Power Switch
A2(-)
A1(+)
L1
T1
Figure 1 - Wiring Diagram for the 905 Series Power Switch
Hoffman|Controls
2463 Merrell Road, Dallas, Texas 75229 • Phone: (972) 243-7425 • Fax: (972) 247-8674 • Toll Free: 1-888-HCC-1190
www.hoffmancontrols.com Form: 173-0245-000 Rev A
5.85
2.50
5.50
5.00
4.50
905
CUTOUT
AREA
2.0
(TEMPLATE TO SCALE)
Old 900 Switch Height 4.00
Figure 2 - Dimensions & Mounting Hole Positions
