Document: 1904en01.doc
QWTIME III IMPULSE AMPLIFIER
Author: PM
Date: 2011-02-03
User Manual
Page: 6 o f 28
WESTERSTRAND URFABRIK AB
P.O. Box 133
Tel. +46 506 48000
Internet:: http://www.westerstrand.se
SE-545 23 TÖREBODA
Fax. +46 506 48051
E-mail:
Calculation of cable area in time systems
General
To make a time system with impulse operated analogue and digital slave clocks perform satisfactory, the cable
from the Impulse Amplifier to the Slave Clocks need to be dimensioned correctly.
A 10% voltage drop is allowed in the cable.
The length and area of the cable and also the current (load) on the cable affect the voltage drop.
Formula
A = l x I x k
A = Area [mm
2
]
l = cable length [m]
I = current [A]
k = 0,015 [constant]
Power consumption
Impulse Slave Clocks
Analogue clocks minute
≤
400 mm: 7,5 mA
Analogue clocks minute
≤
900 mm: 15 mA
Analogue clocks sweep seconds hand
≤
400 mm: 25 mA
Digital Clocks: 4 mA
Time-Code (TC) Slave Clocks
Analogue clocks minute
≤
400 mm:
14 mA
Analogue clocks minute
≤
900 mm:
20 mA
Analogue clocks sweep seconds hand
≤
400 mm, indoor:
12 mA
Analogue clocks sweep seconds hand
≤
400 mm, outdoor:
20 mA
Analogue clocks sweep seconds hand
≤
900 mm:
27 mA
Example
A time system consists of 40 pcs. analogue clocks with diameter 300 mm.
The power consumption will then be 40 x 7,5 = 300 mA = 0,3A.
Cable length is 100 metres.
A = 100 x 0,3 x 0,015 = 0,45 mm
2
Choose a cable with an area of at least 0,45 mm
2
.
