Archive for the ‘Castell switching’ Category

Castell – Company & Product Overview

Monday, April 5th, 2010

Company Overview

Castell Interlocks is the Worldwide Leader in Safety Interlocking. The mechanical and electro-mechanical safety interlocks provide the utmost protection for the man/machine interface in general manufacturing environments. Industries supplied to include utilities, pulp and paper mills, food and drink, textile, steel, feed and packaging. Castell interlocks are also used extensively in the switchgear, power generation and distribution markets.
Trapped key interlocks guarantee the safe operation of plant machinery by forcing a predetermined sequence of events. Forcing the desired procedure eliminates human error, which is a leading cause of industrial accidents. Training costs and other hidden costs are eliminated. Unique die-cast lock centers and/or the non-masterable Q disc tumbler series ensure the integrity of the system and provide personnel with unparalleled protection.
Trapped key interlocks guarantee the safe operation of plant machinery by forcing a predetermined sequence of events. Forcing the desired procedure eliminate

Castell key opperation – Bolt Interlock (Multi key) with Safety Switch

Monday, April 5th, 2010


The bolt movement and the switch condition are directly controlled by the rotation of the keys. The bolt length can be varied to suite the application but the travel of the bolt from extended to retracted is always 19mm. The bolt length should be specified when ordering by quoting the ‘L’ dimension, This being the length of the bolt protruding from the end face with the key in the trapped position and the bolt retracted.
Key Exchange: The Primary Key is trapped, the Secondary Key is free and the bolt is extended. Insert secondary key and rotate, this enbles rotation and removal of the primary key which retracts of the bolt. The retraction/extension of the bolt changes the switch contact condition. The secondary key is now trapped in the lock.
Double Key: The Primary and Secondary Key are free and the bolt is extended. Insertion and rotation of both keys will retract the bolt. The retractio/extension of the bolt changes the switch contacts condition.

Typical System

The Castell KLP is designed to operate as part of an integrated safety system, controlling the operation of HV/LV switchgear or valves. A typical example is shown below.

System Description


The electrical supply to the machine is switched on and the access doors to the hazardous area are locked closed. The initial key is held in the control room and only issued on a ‘Permit to Work’.
To enter the area, the electrical supply is turned off and the initial key inserted into the KLP, which extends the bolt and allows the removal of the secondary key. The electrical supply is now locked in the off position and the contact on the KLP changed to provide visual indication at a control panel of the machine status.
The secondary key is then inserted into the ‘X Key Exchange Box’ to release a further two keys which are used to open the ‘AI’ access locks on the doors. Whilst these keys are out of the ‘X box’, the electrical supply key cannot be removed, ensuring that the power cannot be switched on whilst the access doors are open.

Castell key application – Power Isolation Prior to Multiple Access

Monday, April 5th, 2010

The Castell KP1 switch interlock is designed to operate as part of an integrated safety system, controlling access to hazardous areas. The illustration details the requirement to isolate a valve, which in turn isolates the power to the machine via the machine control circuit.

To gain access to the machine first of all, the valve must be turned to the closed position and locked closed by removing the key. This locks the valve in the closed position and switches the power off to the machine. The key is taken to the X type key exchange box, inserted and trapped. This releases two further keys. These are used to unlock the AI access interlocks mounted on the access points to the machine.

Castell Key application – Power Supply Isolation

Monday, April 5th, 2010

This example shows how to interlock switchgear using the KC claw lock. The same principle can be applied to a number of different applications such as valving or mechanical linkage for machinery applications. In the normal ‘locked off’ operating condition, the claw is extended and the key is free. Inserting and turning the key releases the claw. In this condition, the key remains trapped and the claw cannot be re-extended.


Castell key application – Power Supply Isolation – UPS Switching

Monday, April 5th, 2010

 Assuming the following conditions:

Single Point of Access (Part Body)
Power Supply Isolation – UPS Switching

The Castell KSUPS-20 is a heavy-duty solenoid controlled trapped key interlock switch designed to control access to hazardous machines with rundown times or for use where machinery must complete an operating cycle before the power supply is disconnected. The unit is also suitable for use with uninterrupted power supplies (UPS) to control the changeover of two or more power sources.


In normal operating condition, the switch contacts are closed, the key is trapped and the solenoid de-energised. The key can only be turned and released after the solenoid has been energised via remote electrical signal. Turning the key changes the condition of the switch and releases the key, which can then be transferred to an access interlock. This allows access or entry into the hazardous area.

Castell key application – Transformer interlocking utilising trapped key products

Monday, April 5th, 2010

This arrangement ensures that transformers are isolated and earthed prior to access being gained to the transformer enclosures.

Condition 1
Transformer is locked on with the earth switch locked off and access cabinets locked closed.

Condition 2

Power to the transformer is isolated via an isolator, this releases key ‘A’. Key ‘A’ is taken to the ‘KL’ lock fitted to the transformer ‘ON’ mechanism. The mechanism is switched to the ‘OFF’ position and the key ‘A’ inserted which allows the extension of the ‘KL’ locking bolt and the release of key ‘B’. The transformer is now locked off. Key ‘B’ is taken to the transformer earth mechanism which is moved to the earthed ‘ON’ position and inserted which allows the extension of the ‘KL’ locking bolt and the release of key ‘C’. The earth is now locked on. Key ‘C’ is inserted into the time delay unit ‘D’ and the time delay initiated. The time delay is required to ensure that the capacitors are discharged prior to access. On completion of the delay key ‘D’ becomes available. Key ‘D’ is inserted into the key exchange box ‘X’ to release the access keys ‘E’. Access can now be gained to the enclosures via the access locks ‘D’ and ‘ATE’.