Pulse Echo Based Solenoid Interlock
Schmersal Inc.Posted 04/28/2011
AZM range solenoid interlocks, operating in combination with control elements of a machine, e.g. fail-safe standstill monitors or fail-safe delay timers, ensure that sliding, hinged and removable guarding devices, such as grids, hoods or doors, cannot be opened until hazardous conditions (e.g. running-down movements) have come to an end.
These solenoid interlocks are also used for cases in which the opening of a guarding device represents a non-permissible intrusion in a production process.
AZM 200 Specifications
Design and mode of operation:
On the AZM range solenoid interlocks, the switching element with interlock is not physically connected to the actuator but functionally brought together or seperated on switching. When the guard device is opened in the uninterlocked condition, the actuator is seperated from the base unit. In the process, NC contacts are positively opened and NO contacts closed.
Interlocking is carried out by means of a blocking bolt / latching bolt. This latching bolt blocks the actuator so that it cannot be withdrawn from the interlock. The machine control circuit is only enabled when the actuator has been fed into the interlock and the latching bolt is in the blocking position. This is ensured by contact monitoring of the latching bolt.
There are two modes of interlocking. In the case of "Power to unlock", the latching bolt is held in the interlock by spring pressure. When the de-interlocking coil is energised, the interlock is removed and the NC contacts opened. The guarding device can be opened. For "Power to lock (1)", the mode of operation is reversed.
The AZM 161, 170, 190 and 415 solenoid interlocks are fitted with protection against incorrect locking. Depending on the type of unit, an intergral failsafe standstill monitor, an intergral fail-safe delay timer and individual coding of the actuator are possible.
The solenoid interlocks can be fitted in any desired mounting position. Protection class of the solenoid interlocks is IP 54, IP 65 or IP 67.
(1) In accordance with the policy of the German Technical Assessors, these interlock may only be used after a thorough evaluation of the accident risk, since the guarding device can immediately be opened on failure of the electrical power supply.