GE GE752 manual Brazing Coil Terminals, Gas Torch Brazing

GEK±91584D, Vertical Drilling Motor, Type GE752

NOTE: If a gas torch is used, coil insulation		Machine Brazing
must be protected from heat by a non±flam-		1.	The recommended brazing current is 10,800
mable heat absorbent.
			amperes at 1.6 volts. With silver±solder brazing
1. Pack absorbent around the insulation near			strips inserted between connections, clamp the
	the connection and over adjacent coils.		brazing tongs on the connection and braze the
2.	Make sure all exposed insulation is covered		joint. If necessary, add additional solder to fill the
	with a thick layer of absorbent, then heat and		joint and form a level surface.
	separate the coil connections.	2.	Braze all exciting±coil connections before install-
2.	Heat the coiled frame in an oven at 150￿ C (302￿		ing the commutating coils.
	F) for four hours to soften the varnish so pole	Gas Torch Brazing
	bolts can be removed.
	Remove the pole bolts and the coil±pole assem-	1.	Pack the coil insulation with non±flammable heat
			absorbent material; e.g., interwoven glass cloth.
	bly from the magnet frame.
		2.	Insert the brazing strips and use a C±clamp or vi-
3.	Mark any shims for reassembly with the corre-		se±grip pliers to clamp the connection surfaces
	sponding pole when the coil(s) is installed in the		tightly together.
	frame.	3.	Use a torch tip with a 0.1 in. orifice and adjust the
Coil Installation			torch to obtain a slightly reduced flame. As the
			brazing strips melt, add more solder to fill the
Procedure for New Coil±Pole Assembly			joint and form a level surface.
		4. Remove heat absorbent packing from insulation.
NOTE: Install any exciting coils and braze their
			Use dry, compressed air and blow out the inside
connections before installing commutating
			of the frame.
coils.
1.	Before installing any coil and pole, clean the pole	WARNING: Personal injury may result if prop-
		er eye protection is not worn when cleaning
	contact surface on the frame and the pole piece
		with compressed air.
	mounting surface.
		5.	Torque the pole bolts to the values listed in Table
2.	Install the new pole and coil in the frame with any		3, Page 37, Standard Bolt Torque Values.
	shims that were on the damaged coil. Use new	6. Check the polarity of the field poles:
	washers under bolt heads. Lubricate the bolt
	heads, threads and washers and draw the pole		Energize the field circuit with a battery and check
	bolts moderately tight.
			pole polarity with a compass, Fig. 33.
3.	Refer to Table 2, Page 20, to determine the cor-	7.	Insulate the connections with silicone putty and
	rect coiled frame assembly drawings. All coil		wrap connections with Mylar film (30). Apply
	connections must be brazed with silver solder,		glass tape and extend each taping 1/2 in. beyond
	GE±B20A6. Use two pieces of solder (0.010 x 1		the bare area of the connection. Brush the con-
	in. x 1 in.) between terminal surfaces and braze		nections with air±drying alkyd varnish GE±8001.
	terminals as follows:	8. Install and connect any cables previously re-
Brazing Coil Terminals			moved.
		NOTE: Do not flood±dip the coiled frame before
Braze the coil terminals by one of the following meth-		the cables are installed and the connections are
ods:		insulated.

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