Daktronics Hoist Operation and Maintenance Manual - Manual (Page 4)

1 t HeorY oF operation
The hoist is connected to the main high voltage power buss through a hard wire connection
from the building power distribution system. This connection brings in the main 240 VAC,
3-phase power that is connected to the motor contactors and motor brake located in the hoist
assembly. The high voltage power originates in the Hoist Remote Power Panel, and is wired
to the hoist assembly through 1/2" conduit. The hoist low voltage 24-volt DC control and
E-stop circuit are also provided from the Hoist Remote Power Panel and are wired to the hoist
in 3/4" conduit.
The variable frequency drive controls all movements of the hoist. The S Series controlled hoist
with push button control runs in open loop and is controlled at the remote control station
with momentary push buttons. The hoist is protected via hardwired UP and DOWN control
signals, hard struck limit switches, emergency stop status and optional over/under capacity
sensors. The UP and DOWN control signals to the variable frequency drive for the direction
to run the hoist (Figure 1). The limit switches are used for maximum up and down travel.
The emergency STOP status is
used to detect the operation of
the emergency stop system and
the optional over/under capacity
sensors will ensure that the hoist is
being operated within its designed
capacity.
Housed within the hoist power
panel is a 24-volt DC power supply
that powers the control circuit
and the E-Stop circuit. A fused
disconnect and a master control
contactor are also mounted inside
the hoist power panel. The 24-volt
DC E-Stop circuit is connected to
the E-STOP button located on the
front of the master control cabinet
as well as the E-STOP button
located on the pendant, if
applicable.
01
tHeorY oF operation
FIGuRe 1: S Series remote control station