Johnson Controls CK721-A User Manual

Figure 3-26: Field Installed Metal Oxide Varistor
A full line of varistor components is available
from Harris Semiconductor (now
Littelfuse Corp.).
S300 Expansion Enclosures CK721-A Installation and Operation
3-36 24-10349-8 Rev. B
This document contains confidential and proprietary information of Johnson Controls, Inc.
© 2012 Johnson Controls, Inc.
Door Strike Wiring
The door strike relay is located at J1 and J4 on the reader module.
Some door strikes are fail-secure or fail-locked. These door
strikes energize to
unlock the door and de-energize to lock the door. These strikes must be connected to
the strike power source through the normally-open contacts of the strike relay (NO
and C, pins 12 and 11).
Other door strikes are fail-safe types that energize to lock the doo
r and de-energize
to unlock the door. These strikes must be connected to the strike power source
through the normally-closed contacts (NC and C, pins 10 and 11).
The maximum length of door strike wiring depen
ds on the power requirements of
the strike or latch. The resistance of the #18 AWG wire must not reduce the voltage
to the strike by more than 10%. The lock’s current ratings should not exceed 2
amperes at 30 VDC.
To insure proper operation and to extend the contac
t life of mechanical relay outputs
(RDR2 STRIKE), the contacts should be protected by an external protection circuit.
This protection circuit is application- specific as configured in the field. Johnson
Controls would advise, at a minimum, a Metal Oxide Varistor (MOV) at the rated
voltage relative to the application across the power source and power load
interrupted by the mechanical relay.
+

+

+V
V
+V
V
CNC
NO
Strike Relay
Source
Power
Load
Power
Field Installed
Metal Oxide Varistor

Johnson Controls CK721-A Specifications

General

Brand	Johnson Controls
Model	CK721-A
Category	Controller
Language	English