Baldor mn722 manual Ungrounded Distribution System, Input Power Conditioning

Figure 3-2 Recommended System Grounding – EK

JOG	LOCAL	PROG
FWD	DISP
REV	SHIFT	ENTER
STOP	RESET

Note: A boost regulator is required and			Series H
				Note: Wiring shown for clarity of grounding
	provided with each model EK control.
Note: A line reactor is required and				method only. Not representative of
				actual terminal block location.
must be ordered separately.			L1 L2 L3	T1 T2 T3
				Note: A load reactor is highly recommended
AC Main	L1			and must be ordered separately.
Supply		Line	Boost	Optional
	L2	Reactor	Regulator
				Load
				Reactor
	L3
Safety	Earth
	Four Wire
Ground
Driven Earth	“Wye”
	Route all 4 wires L1, L2, L3 and Earth
Ground Rod
	(Ground) together in conduit or cable.
(Plant Ground)
				Ground per NEC and
		Route all 4 wires T1, T2, T3 and Motor
		Ground together in conduit or cable.		Local codes.

Connect all wires (including motor ground) inside the motor terminal box.

Ungrounded Distribution System

With an ungrounded power distribution system it is possible to have a continuous current path to ground through the MOV devices. To avoid equipment damage, an Isolation transformer with a grounded secondary is recommended. This provides three phase AC power that is symmetrical with respect ground.

Input Power Conditioning

Baldor controls are designed for direct connection to standard three phase lines that are electrically symmetrical with respect to ground. Certain power line conditions must be avoided. An AC line reactor or an isolation transformer may be required for some power conditions.

SBaldor Series H controls require a minimum line impedance of 3%. Refer to “Line Impedance” for additional information.

SIf the feeder or branch circuit that provides power to the control has permanently connected power factor correction capacitors, an input AC line reactor or an isolation transformer must be connected between the power factor correction capacitors and the control.

SIf the feeder or branch circuit that provides power to the control has power factor correction capacitors that are switched on line and off line, the capacitors must not be switched while the control is connected to the AC power line. If the capacitors are switched on line while the control is still connected to the AC power line, additional protection is required. TVSS (Transient Voltage Surge Suppressor) of the proper rating must be installed between the AC line reactor or an isolation transformer and the AC input to the control.

3-6 Receiving & Installation MN722