Installation, Operation and Maintenance Manual
8221 RevD 08-18
8
For example, suppose a 480V three phase motor appears to be connected as a 480V Delta. In
actuality, the serving distribution system might be a 480Y/277V grounded Wye, with or without a
neutral pulled to the motor or MCC. The system is still a 480Y/277V Wye, even though the load is
connected as a Delta. A grounded Wye has a defined reference to ground (i.e., neutral is bonded
to ground). In contrast, some Delta systems are ungrounded, which have no reference to ground.
SPDs on Ungrounded Systems
Caution – Ungrounded systems are inherently unstable and can produce excessively high line-to-
ground voltages during certain fault conditions. During these fault conditions, any electrical equipment
including an SPD, may be subjected to voltages which exceed their designed ratings. This information
is being provided to the user so that an informed decision can be made before installing any electrical
equipment on an ungrounded power system.
FIGURE 5: DIMENSIONS & WEIGHT
3.26”
3.26”
1.15”
4.13”
3/4”-14
Sized for std 35mm DIN-Rail
3.31” 3.57”
Weight: 1.60 lbs
(0.73 kg)
FIGURE 6: S50A MOUNTING OPTIONS
Bracket Mount
for flat surfaces
Std. 3/4”-14
Nipple
DIN-Rail Mount
(rail not incl.)
If standard front facing label is not
viewable when installed, unit may be
installed so side label is front facing.
• 3/4” pipe nipple (conduit nut included)
• With L-bracket mounting kit accessory
- Standard 35mm DIN-Rail (not included)
L-bracket tightens onto DIN-Rail
- Standard flat mounting surface
Attach L-bracket to surface via
mounting holes
