GB1224326A - Improvements in or relating to coil winding apparatus - Google Patents

Abstract

1,224,326. Making electrical windings. AVO Ltd. 11 Nov., 1969 [12 Nov., 1968], No. 53557/68. Heading B3A. In coil winding apparatus, which includes at least one coil forming die M1, M2 of electrically conductive material and means for supplying electric current to a coil L1 of insulated wire on, or in, the die to heat and thus soften a thermoplastic coating on the wire, means are provided for automatically disconnecting the current supply if the wire comes into electrical contact with the die. If a short circuit occurs between the coil L1 and either of the dies Ml, M2, current will flow from a D.C. source through the energizing coil of a relay RL1 causing the relay to operate and open a contact 1/1. As a result, a bonding contactor BC will be de-energized to open contacts C1, C2, thereby disconnecting a transformer T1 from the mains supply. At the same time contacts 1/2 will close to hold the relay RL1 operated. A resistor R1 limits the current flow under short circuit conditions, such current coming from the D.C. source. To reduce overloading on the relay coil before the relay operates when a short circuit occurs in the region X of the dies M1, M2, the relay coil may be connected to a centre tap on the secondary winding instead of to one end of the winding, Fig. 2 (not shown). The short circuit current may be still further reduced by the inclusion of resistors (R3), (R4) between the centre tap and the contact 1/2. A normally closed contact (1/4) may be included on the relay to stop the winding motor as soon as a breakdown of insulation occurs.