Malfunction detector
First Claim
1. A malfunction detector for detecting a malfunction in a machine having switch responsive to an operational parameter of said machine, said malfunction detector comprising:
- supplying means for supplying an alternating current test signal to said switch means, said supplying means comprising generating means for generating said alternating current test signal with a frequency equal to the product of a mains frequency and a positive non-zero integer and with a phase which is shifted by a predetermined amount with respect to said mains phase; and
determining means for determining whether the resistance of said switch means to said alternating current test signal exceeds a threshold value, said determining means comprising phase detection means for responding only to a detection signal from said switch means having the same frequency and phase as said alternating current test signal.
0 Assignments
0 Petitions
Accused Products
Abstract
A malfunction detector is connected to switches provided in a machine, such as a punch press, for actuation when a malfunction occurs. The detector is capable of supplying an alternating current test signal to the switches and determining whether the resistance of the switches to the test signal is greater than or less than a threshold value. The test signal preferably has a frequency which is equal to mains supply frequency or a harmonic thereof and the malfunction detector preferably only responds to changes of state of the switches during specific time windows.
-
Citations
7 Claims
-
1. A malfunction detector for detecting a malfunction in a machine having switch responsive to an operational parameter of said machine, said malfunction detector comprising:
-
supplying means for supplying an alternating current test signal to said switch means, said supplying means comprising generating means for generating said alternating current test signal with a frequency equal to the product of a mains frequency and a positive non-zero integer and with a phase which is shifted by a predetermined amount with respect to said mains phase; and determining means for determining whether the resistance of said switch means to said alternating current test signal exceeds a threshold value, said determining means comprising phase detection means for responding only to a detection signal from said switch means having the same frequency and phase as said alternating current test signal. - View Dependent Claims (2, 3, 4, 5, 6, 7)
-
Specification