7
Insert Availability
22
24
Rating 3
Sea Level
1013 mbart
8500m (27,900 ft)
320 mbar
21,340m (70,000 ft)
44 mbar
Working Voltage
Working Voltages ** (nominal)
d.c. or a.c. peak
Voltage Proof
d.c. or a.c. peak
III
1500
3000
III
800
1300
III
450
750
Altitude
Sea Level
300mb at 20
o
C
8.500m
(27,800 ft)
44 mb at 20
o
C
20,000 m
(66,000 ft)
Rating 2
Sea Level
300mb at 20
o
C
8.500m
(27,800 ft)
44 mb at 20
o
C
20,000 m
(66,000 ft)
Voltage
700
375
200
1250
550
300
Voltage r.m.s.
500
265
140
900
390
210
Proof Voltage
500
265
140
3250
1750
775
FLASHOVER VOLTAGE kW
4
3
1
0
20
(6)
40
(12)
60
(18)
80
(24)
100
(30)
120
(36)
140
(42)
160
(48)
180
(54)
THOUSANDS OF FEET (METRES)
Relationship between flashover voltage and altitude
for each voltage rating
(Figures in bold type are from DEF STAN 59-35 (Part 1) Sec. 3 Patt. 105)
Because safe working voltages at altitude above sea-level are dependent upon individual
conditions of use, these values are not specified in DEF STAN 59-35 (Part 1) Sec. 3 Patt.
105 but approximate values are included here for the guidance of designs.
VOLTAGE RATINGS
Two categories of voltage rating are specified in DEF STAN 59-35 (Part 1) Sec. 3 Patt.
105.
Rating 1 (700V d.c. working at sea-level)
Applicable to the high contact density inserts shown in the upper section of the insert
availability diagram above.
Rating 2 (1250V d.c. working at sea-level)
Applicable to the inserts shown in the lower section of the insert availability diagram.
Rating 3 (1500V d.c. working at sea-level)
(a) Maximum current per individual contact (in isolation)* at ambient temperature of 85
o
C
Contact Size 12: 23A
(b) Maximum current per contact through all contacts simultaneously at an ambient
temperature of 85
o
C
Contact Size 12: 20A
Altitude Derating
Information on voltage derating for operation at altitudes above se-level can be obtained
from the flashover voltage altitude curves on the left.
VOLTAGE RATING 2
VOLTAGE RATING 1
Working Voltage