Baldor Baldor, MN850 Control Supply, Motor Overload and Thermal Protection, Digital Soft-Start

Figure 2-1 Power and Motor Circuit Connections

115/230VAC		Note 1		L1	L2	L3 Earth			L1	L2	L3
Note 2	*								Alternate *
	OT		* Circuit						Fuse		Note 1
	or								Connection
	*		Breaker
	OL
		* Input					Note 3
	Note 6			IC
		Contactor							* Optional components not provided with control.
							Note 4, 8
				L1	L2	L3
			S1	Programmable			X1	115/230VAC
			S0
							X2
				Input				Note 5, 6
	K1 is factory preset		14		Baldor		Notes:
	as the •RUN" relay.				Digital
			11	K1
			12		Soft–Start		1.		See “Protective Devices” described previously in this section.
			24				2.		Motor Overload and/or Thermal protection is required by NEC.
			21	K2			3.		Use same gauge wire for Earth ground as is used for L1, L2
			22
									and L3.
				T1	T2	T3	4.		Metal conduit should be used. Connect conduits so the use of
									a Reactor or RC Device does not interrupt EMI/RFI shielding.

Note 2

	T2	T3
115VAC	* AC Motor T1	G

*

Note 7 OT

Motor Thermostat Leads

5.X1 and X2 control terminal power must be present or the logic circuits will not work. Either 115VAC or 230VAC can be used. Be sure the 115/230VAC switch (Control Voltage Selector Switch) is set to the proper voltage before you apply power.

6.The X1 and X2 control voltage input has different VA ratings depending on enclosure size, see Table 2-3.

7.Add appropriately rated protective device for AC relay (snubber) or DC relay (diode).

8.To protect the control, be sure to add MOV protection. Refer to Appendix D for additional information.

See Recommended Tightening Torques in Table 2-4.

All soft–starters require a separate fused 2 wire, single phase connection at terminals X1 and X2. An external fuse is required and must be sized as described in Table 2-3. Either 115VAC (98 – 126VAC) or 230VAC (196 – 253VAC) input may be used. The control voltage selector switch allows simple selection of 115VAC or 230VAC input power.

	Table 2-3	Control Supply
Chassis Size	Current Rating		Nominal Power Consumption	115V Fuse	230V Fuse
	(Amps)		(VA)
	to 23A		8VA	125mA	63mA
Size 1	30A to 44A		10VA	200mA	100mA
	59A to 146A		12VA	200mA	100mA
Size 2	174A to 370A		18VA	200mA	100mA
Size 3, 4	500A to 1200A		8VA – Control card	125mA	63mA
			140VA – separate fan supply	2A	1A

Motor Overload and Thermal Protection

NEC and local codes may require thermal motor overload protection devices be installed rather than rely only on internal protection devices. Devices such as bi–metallic overload relays may require special Soft–Start settings (such as during low voltage starting to prevent heating). Use of electronic overload relays with this control is not recommended because of the distorted current waveform. A motor with built in thermal cutoff switches (TSTAT’s) is recommended.

2-6 Installation MN850