Operations Model 6DS-SP Planarizer
1 - 20 Version 4.0 - February 1998; Update 10/19/01
MODEL 6DS-SP INTERLOCK SYSTEM
There are six coded magnetic switch devices connected to the EMO safety
relay. These magnetic switches are located on the four lower access panels,
and on each door of the large electrical cabinet. Each magnetic switch
device consists of one "sensor" and one magnetic "actuator". Each sensor
contains one set of normally open (NO) contacts and one set of normally
closed (NC) contacts. The sensor must be used with a matching magnetic
actuator in order to function. These matched sets drastically reduce the
ability to defeat the sensor by a simple magnet.
The coded magnetic switches are designed to function only with a safety
relay. The safety relay monitors both the NO and NC contacts of the
magnetic switches. Whenever one of the four lower access panels, or one of
the two large electrical cabinet doors, is not in place, the safety relay opens
the output contacts. This disconnects power to the coil of the main contactor
and thus disconnects power to the main part of the machine.
A control unit monitors the status of the main contactor. The main contactor
is a safety contactor
designed with "mechanically linked, positively guided
contacts". One of the normally-closed auxiliary contacts is connected to the
monitoring circuit of the control unit. The control unit will not close the
safety output contacts unless all the magnetic switches are correctly situated
and the NC contacts of the
main contactor
are closed. This style of contactor
ensures that, in the case of welded main contacts, the machine cannot be
powered on until the welded-contact condition is corrected.
The power required to ensure function of this circuit is fed by a 24VAC
circuit, which is not affected by an emergency power-off condition.
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