IKDV01 Keypad Push Button System
Issue: R4 Date: 03/2020, ECN: 9436
IKDB003 R4
IKD Keypad Pushbutton System User Manual.docx
Page 8
To add further safety to the Keypad / Interface system, a “watchdog timer”, continually tries to open the stop relay
output contact. If the keypad system is functioning correctly, the timer is being continually reset and the output
remains closed.
CAUTION!
To enable the additional safety feature of the “watchdog timer” to be fully utilised it is
important that the stop relay output contact be used in the control circuit.
5.2
Start
When the Start key is pressed the Start opto-isolated output turns on. This output is connected to the start input
(terminals 25 and 26) on the Integrated Protection Relay. This function is ignored unless the stop key has been
operated following power up.
5.3
Lock
Before the Lock key is operative the I.S. Digital Input must be closed to allow the lock key to function. The I.S. Digital
Input (located on the rear of the Keypad Module) is intended to be connected to a push button which is either locked
or behind a lockable cover, to prevent unauthorised operation.
Operation of the Lock key causes the lock opto-isolated output to turn on. This output is connected to the lock input
(terminals 21 and 22) on the Integrated Protection Relay.
5.4
Reset
Operation of the Reset key causes the reset opto-isolated output to turn on. This output is connected to the reset
input (terminals 23 and 24) on the Integrated Protection Relay.
5.5
Earth Continuity (E/C) Test
Operation of the E/C Test key triggers the test operation contacts, which are connected into the pilot circuit.
The test alternates between an open circuit and a short circuit on the pilot line. The alternations occur every 2
seconds. This can be observed by viewing the Earth Fault Information Pages on the Remote Display Unit of the
Integrated Protection Relay.
If the Stop key is pressed simultaneously with the E/C Test key, a diode is switched between the pilot and earth to
perform a “Relay Healthy” test. This allows the operator to determine if the fault is in the DCB or in the external
circuit.
When this test is performed the Stop relay remains off for 1.5 seconds after the E/C Test key is released.
5.6
Earth Fault Lockout (EFLO) Test
Operation of the EFLO Test key allows external test resistors to be switched between VcmA, VcmB, and VcmC
terminals (3, 4 and 5 on the Integrated Protection Relay) and earth.
To perform this test the Start key must be operated while holding the EFLO Test key operated.
