10
JMNC Operating Instructions
3 Design and Function
3.2
Function Principle of the JMNC
3.2.1
General
In connection with a rotational speed indicator, the rota-
tional speed monitoring device JMNC is used to monitor
drives for underspeed, standstill, or overspeed.
The pulses of the rotational speed indicator are ana-
lysed by the monitoring device, which signals the under-
speeding or overspeeding of a set nominal rotational
speed.
The indicator input (
17
) (terminals 1/2) of the rotational
speed monitoring device is designed for rotational speed
indicators complying with the npn and Namur regula-
tions. The indicator input (
17
) can be monitored by
means of the light-emitting diode LED orange (
4
).
Any number of monitoring devices JMNC can be con-
nected to one pulse indicator.
The output relay (
16
) of the rotational speed monitoring
device is a change-over contact. The current switching
status of the relay is indicated by the light-emitting diode
LED green (
5
).
In addition, the rotational speed monitoring device JMNC is
provided with a pulse output to connect common digital ro-
tational speed counters
(see section 5.3.1, Connection As-
.
3.2.2
Run-up Bridging
In order to start up the plant, the rotational speed moni-
toring device JMNC is provided with the feature run-up
bridging.
By means of the potentiometer start-up delay (
1
) the pe-
riod of the run-up bridging can be set in between 0 and
45 seconds. During this time, the output relay (
16
) re-
mains attracted, and the plant can be started.
Type
Number/switch-over contact
JMNC
1 x change-over contact (open contact/closed
contact)
